Rome and the Economic Integration of Empire

Ancient Wheat Prices and Market Mechanisms

In several recent publications, Peter Temin has advocated the view that the Roman Mediterranean area was a single market, by studying the credit, labor and goods markets.³⬈#p1

In this paper, we will focus on the last of these. This is not to say that the other two topics are of no interest--far from it. But they require, especially for interest rates, specific numerical analysis that we hope to present in a future paper.⬈#p2

The grain market was undoubtedly the largest market by volume in the ancient Mediterranean world, although we cannot be certain it was always the first in value. A single ship engaged in the Indian trade was able to carry close to HS 10 million in value. This is equivalent to about 2.5 million modii of grain at the likely second-century A.D. Italian price and 4 million modii at Egyptian prices. This is about the volume of the entire annual Sicilian first tithe as reported by Cicero.⁴⬈#p3

The relatively low volumetric value of wheat may explain why we have little or no evidence about wealthy merchants specializing in the grain trade, although we have numerous examples linked with the luxury, oil, or wine trades.⁵ Numbers from hagiographic sources in the 6^th and 7^th centuries, for what they are worth, imply that the value of some precious cargos could exceed that of regular wheat loads by a factor of five to fifteen.⁶ Eventually, since the administration of the Roman and Constantinopolitan annonae owned a significant share of the grain that was transported by sea, it may well be that, although grain did represent the most important good transported in volume terms, it was not the most important traded good when accounted for in value.⁷⬈#p4

Nevertheless, the sheer importance of grain as the universal subsistence commodity of the Mediterranean area at this period led to some price recording. Although quite scattered and very often linked to crisis situations, these prices or indications of prices of grain in different contexts create a clear temptation for testing whether or not grain price behavior would fit within a global integrated market process. Grain offers the potential for price comparison since its quality and type had necessarily a much more limited impact on its median price than was the case for wine or oil, for instance.⁸⬈#p5

The “Temin Equations” of a Centralized Efficient Roman Market for Grain

In his 2006 article, extended in 2008 with the collaboration of David Kessler,⁹ Peter Temin uses various wheat “prices” essentially gathered by Geoffrey Rickman in his influential 1980 book The Corn Supply of Ancient Rome. From these a set of price differences between “Roman” prices and selected prices from outside Rome is built, and a linearity test between price differential and distance from Rome is run. The aim is to produce a linear relationship between price differentials and distances by means of the OLS (Ordinary Least Squares) methodology. This being achieved with a high degree of statistical confidence, the argument leads to the conclusion that the farther we are from Rome, the cheaper the grain becomes, since “the price would have been set in Rome where the excess supplies and the largest excess demand came together” and “wheat outside Rome would be valued by what it was worth in Rome,” the main component explaining the difference being transport costs.¹⁰ This would vindicate the view that Rome and to a lesser extent Italy would have been at the center of an integrated Mediterranean economy.⬈#p6

Free profit-driven traders, having to deal with Roman demand on the one hand and various supply areas on the other, while competing against each other, would have had to purchase wheat where it was the cheapest, transportation costs included. By doing so, they would have encouraged the comparatively cheaper areas to produce more and put pressure on the most expensive producers to reduce their own costs, effectively aligning distance-to-Rome-adjusted wheat prices all across the accessible wheat producing regions of the Mediterranean area. Implicitly, that commercial pressure would have affected wages and other prices altogether, the process of reaching the market equilibrium mainly involving emigration and agricultural shifts in the least competitive regions, while in the best positioned areas more marginal land would have been dedicated to wheat, increasing marginal costs over time. This is how the relationship between price differentials and distance to Rome would prove the existence of a single integrated free market operating at the scale of the entire Imperial area or, to use the author’s own words, “a single monetary market and a single wheat market across the whole Mediterranean.”¹¹⬈#p7

An economy of trade centered on the city of Rome and, to a lesser extent, Italy would vindicate the “Tax and Trade” model advocated by Keith Hopkins and further developed by Hans-Ulrich von Freyberg. Rome would benefit from taxation intakes; the influx of liquidities would push local prices higher, making local goods too expensive. Producers from all over the Empire would exploit their comparative price advantage and outperform their Italian competitors.¹²⬈#p8

Temin and Kessler’s figures, showing a broadly negative linear relationship between distances from Rome and grain price differential, can be summarized as follows:⬈#p9

This leads to the following chart between prices differentials and distances from Rome:¹⁴⬈#p10

The rather neat linearity observable between price differentials and distance from Rome would imply the following relationship:⬈#p13

where β is the multiplicative coefficient linking the distance from Rome to the price differential, α the constant, both factors minimizing the standard deviation between the linear regression results and the actual data, and ε the statistical residual of the equation, i.e.. what is left “unexplained” by the equation produced by the regression computation. The numerical results obtained by the authors eventually fit well with that linearity pattern:¹⁵⬈#p15

This would imply the dominance of market mechanisms, by which prices would be higher where demand is the highest and supply most constrained, whereas remote places far away from the center would enjoy a cheaper life. This is indeed a very seductive vision: Braudelian in the sense that Rome would emerge as the focal point of a wide web of merchant activity, as Bruges, Anvers, Venice, Genoa, Amsterdam, Paris, London, and New York were to become during pre-modern and modern times.¹⁶ Moreover, by introducing statistical treatment and a modern economic approach into the study of the ancient economy, Peter Temin opens the door to a completely renewed approach to ancient history, using numerical analysis, a field where most ancient historians have shown some degree of reluctance.⬈#p16

By doing so, David Kessler and Peter Temin clearly expose themselves to criticisms, of which they seem to be mostly conscious. This is how they address them:⬈#p17

• Ancient data are uncertain. Nevertheless, they can be treated as reliable since they are “mentioned in a surviving document” or because “Polybius was a very careful historian.”¹⁷
• Distance in itself is not that relevant, in the sense that sea, river and land transportation costs are very different. Hence, the Po valley price is eliminated in a second run.¹⁸
• Lower prices outside of Rome would have been explained by low monetization.¹⁹ Although this may be true in Lusitania, that factor could not have explained the low prices in Egypt, where coins were very abundant.²⁰
• Data may be unreliable, reflecting extreme and crisis conditions as well as being subject to unknown seasonal variations or literary invention. But “travelers were told of the prevailing prices.”²¹ Supporting this rebuttal is the fact Rickman was careful to exclude the extreme observed prices from his conclusions regarding average prices.²²
• The argument could be circular if “we assume the data are sound because they support the hypothesis,”²³ but these prices are simply a true random sample.
• Data are too few. Nevertheless, the level of statistical confidence is compared to minimum levels required for limited samples and degrees of freedom and bodes well.

In reality, most of these issues remain serious hurdles and need to be addressed with a less superficial scrutiny.⬈#p18

The Law of Small Numbers

Everybody is familiar with the Law of Large Numbers, which consists of performing the same experiment a large number of times in order to observe a close approximation of a probabilistic solution. By contrast, there is no such law for small numbers: small samples being less likely to be bulletproof, statisticians try to avoid situations where they have to rely on a dozen or fewer observations. A relatively recent paper went so far as to suggest as a rule of thumb that we should not study samples with fewer than twenty observations when faced with two variables, including the constant.²⁴ Without entering into technical niceties, the main issue is that few available parameters do not allow the error term in the equation to sufficiently converge towards the true term, implying a significant loss of information.⬈#p19

Even when statistical quality may seem on the surface to be satisfactory, the results might differ from what a larger sample would produce. Because the equations run by Kessler and Temin contain between 5 and 6 parameters and 2 unknown coefficients, we are exactly in that situation.⬈#p20

The second issue that arises when conducting any analysis of that kind is the comparability of the “statistics.” If different measuring tools or concepts are used in gathering the numbers that are to be statistically studied, comparability distortions arise, and results are therefore affected.²⁵⬈#p21

The dataset used by Kessler and Temin contains one obvious source of incomparability: most prices are observed in rural contexts, with the exception of Antioch in Pisidia and the estimations for Rome. The sales margin applied by the urban retailers should theoretically be deducted from these two prices to make them comparable. One argument against doing so is that the prefect in Antioch may well have addressed wholesalers’ prices rather than retail and that the Roman retailers’ margin will have been reflected in the constant factor of the equation. We will revert later to that topic.⬈#p22

Another major issue, particularly with limited samples, is what statisticians call the heteroscedasticity of the variables. This occurs when the measurement uncertainty of the observations differs from one to another.²⁶ The typical way to handle this issue is to run weighted ordinary least squares, where the most uncertain inputs are inversely linked to their reliability by decreasing their impact on the final results.²⁷⬈#p23

In the case of these ancient prices, we are clearly faced with such an issue, because of the heterogeneity of the observation process itself. For instance, at Antioch in Pisidia, the customary price is indicated in the Prefect’s edict itself.²⁸ Egyptian prices are rather well documented as well through numerous surviving papyri, although this does not prevent issues from arising. For instance, the Egyptian price sample selected by Kessler and Temin relates to the years A.D. 45-46. However, there was a famine in 45-47 as a result of the excessive inundation of 45. Temin and Kessler are aware of this but decided to use this sole piece of Egyptian evidence. Interestingly, Dominic Rathbone returned in a more recent work to this topic and opted for a wider and later period of observation, A.D. 80 – 160, which yields a median price of 9 drachmas per artaba. This price, equivalent to HS 2 per modius,²⁹ is 33% higher than the level used in their equation by Kessler and Temin and illustrates the high variance of the input data.⬈#p24

When we move from primary into secondary sources, the exercise becomes potentially even more unreliable. Although one may argue, with some justification, that Cicero (in the midst of a trial) and Polybius (because of his accuracy) are to be followed, it is quite clear that prices derived from literary sources are of a different nature from prices provided by primary materials recording real transactions.⬈#p25

The case of the Lusitanian price is illustrative: the relevant fragment of Polybius’s Histories has been transmitted through the later 2^nd-century A.D. Alexandrian sophist Athenaeus. The price of barley is given as “1 drachma” and the price of wheat as “9 Alexandrine obols.”³⁰ The word “Alexandrine” is a cause of concern, since it is highly unlikely that the Achaean Polybius would have used the Ptolemaic currency, whose use was restricted to Egypt, to translate a grain price in Cisalpine Gaul while addressing an aristocratic Greco-Roman audience.⬈#p26

Athenaeus might have turned Polybius’s 9 (Attic) obols into 9 “Alexandrine” (Ptolemaic) obols, knowing that the Egyptian currency was at that time locally translated at par against other Hellenistic coinage.³¹ In that case we have 1 medimnos = 1.5 drachma = 1.5 denarius = 6 sestertii. Then the modius is worth slightly over 1 sestertius, since 6 modii are a little over 1 medimnos. Alternatively, 9 Alexandrine (Ptolemaic) obols could be equated with 7.5 to 8 Attic obols after taking into account their lower silver content, and the modius would have been worth a figure close to HS 0.85 This is evidently the solution chosen by Rickman, since he writes “just less than 1 sesterce a modius.”³² As such, this is the figure that Kessler and Temin use.⬈#p27

However, if Athenaeus is paraphrasing Polybius and using the drachma and obol of the Roman Egypt that he and his audience knew, then 9 Alexandrian obols simply means HS 1.5 in the 2^nd century A.D., i.e., 3/8 denarius for a medimnos, since at that time 1 Attic drachma = 1 denarius = 4 sestertii = 4 Alexandrian drachmas. In that case, Polybius would have originally written 2.25 (Attic) obols and Athenaeus would have translated this into something more customary to his Alexandrian readers, provided he was aware of the way these different monetary systems were translated into one another. If this is correct, the price of a modius of wheat in Lusitania in the 2^nd century B.C. could have been as low as HS 0.25 instead of slightly below HS 1.⬈#p28

But the question is still not exhausted, for when Polybius was writing, the Romans modified their currency system and the denarius was revalued from 10 asses to 16 asses in c. 141 B.C.³³ Since Polybius once approximates 1 obol with 2 asses,³⁴ it is quite likely that he uses the pre-141 system where the sestertius was worth not 4 asses but 2.5 asses. As the sestertius remained a quarter of a denarius, this does not change the price translation computed by Rickman. Nevertheless, it is legitimate to question whether actual prices in copper currency did not rise by 60% during the years following the moment when the value of the denarius had been adjusted upward by 60% vs. the as. This would undermine the comparative character of the prices stated by Polybius just before the monetary reform.⬈#p29

It is possible that the Roman authorities adjusted their bimetallic monetary system to the actual market rate of exchange between their silver and copper currency at that time.³⁵ The price computed by G. Rickman could thus be correct. Nevertheless, this example should remind us that ancient “numbers” are not always what they appear to be.⬈#p30

We must also face the issue of prices in the city of Rome. Available estimates offer quite a wide range, from HS 3 to 10 per modius. Rickman, whose work on Roman prices is Kessler and Temin’s nearly unique source, wrote: “the essence of our problem of course lies at Rome,” and “there is no evidence at all for ordinary prices of grain at Rome in the late Republic … The situation is no better for Augustus.”³⁶⬈#p31

Indeed, we need to remember that we do not know any wheat price in Rome, and that all these “numbers” derive from scattered indications of State sponsored prices observed during unusual times between the 3^rd and 1^st centuries B.C., combined with the HS 2 subsidy offered by Tiberius as a reciprocity for capping prices, and the (low) price of HS 3 imposed by Nero in the aftermath of the great fire.³⁷ Practically speaking, the prices in Rome could have averaged HS 4 or 8 at the beginning of the Principate without modern historians having any convincing way to reduce this level of uncertainty. The closest we can get is by following Richard Duncan-Jones and reducing the price range to HS 6-8.³⁸ This is still a 30% margin of error and an exceptionally high degree of data instability.⬈#p32

Interestingly enough, the same can be said about the median wheat price in Palestine, which, according to Daniel Sperber, opposing here Heichelheim’s readings, would have been close to 1 denarius (HS 4) per modius. This is twice as high as in Egypt instead of being 50% higher.³⁹⬈#p33

The sheer size of the uncertainties surrounding the explicative parameters then leads to even bigger dangers: data errors may be so large that different empirical findings could be supported with the same degree of likelihood.⬈#p34

Contemporary econometrics offer an interesting example of how a single error can significantly modify findings when data samples are small: Christina Romer, in an attempt to correlate wealth with durable goods consumption in the 20^th century, was using about 30 pre-war data and a little bit under 45 post-war parameters reflecting the US stock index. The pre-war and post-war results showed significant unexplained differences. The cause of these was eventually found to be a single wrong observation within the post-war S&P 500 series.⁴⁰⬈#p35

If one wrong parameter may have such an influence on a regression supported by about 40 data points, what might happen when the number of explicative parameters is reduced to 5 or 6?⬈#p36

Alternative relationships or absence of relationships?

To test the robustness of the model, I will use most of the parameters of Kessler and Temin, adjusting only those that seem the most clearly debatable. Notably, we will not change the Roman prices at this stage, since their level of uncertainty over the two centuries that are considered is just too wide to easily support any tighter and more relevant median estimate. It could even be argued that the average price does not matter very much, since we are aiming at a relationship between a price differential and a distance. Any shift in the Roman figure would simply translate into the constant factor of the equation, β.⬈#p37

What matters the most is actually whether the level of general prices in Rome did rise at all between the Late Republic and the Early Empire, since that assumption does have an influence on the actual correlation factor. Kessler and Temin assume a general rising trend that leads from HS 3.5 per modius during the 2^nd century B.C. towards 5.5 in the 1^st century A.D., finding some support in Rickman and Rathbone’s previous works.⁴¹ I will not challenge that assumption here, although some caution is to be advocated. To quote Rickman: “It is possible that by the end of the Republic and the early Empire, the price of grain in Rome had risen to a regular level of 5 or even 6 sesterces a modius.” As far as Egyptian prices are concerned, Rathbone argues for broad stability between the later first century A.D. and 160. Then his argument develops further, since “even the prices attested before A.D. 50 mostly fall within the later normal band, but they may represent a lower band of prices.”⬈#p38

Even that cautious assumption of a rise is potentially challengeable by the uncertainties surrounding the rate of exchange between the later Ptolemaic and early Imperial Egyptian drachma and the Imperial currency. The weight of silver in the Egyptian tetradrachm dramatically dropped from Ptolemy XII until Nero, from close to 12 grams before 50 B.C. to a 3.4 grams median weight under Tiberius and 3.1 grams under Claudius, before the Neronian reform brought it down to around 2.5 grams. The one to four rate of exchange between the denarius and the drachma is actually only attested from the later 1^st century A.D. onward.⁴² Strictly speaking, it is thus difficult to prove that Egyptian prices converted in Roman units of value rose at all between the later Ptolemaic/early Imperial period and the 160s. We will come back to that topic.⬈#p39

For the sake of argument, let us nevertheless maintain the Roman price increase as assumed by Temin and Kessler. There remain three prices that they use outside Rome that need some obvious revision: those from Palestine, the Fayyum, and Antioch in Pisidia.⬈#p40

Equation instability with two prices’ adjustment

As previously seen, Palestine’s prices were most likely closer to HS 4 than 2-2.5 per modius. As far as Egypt is concerned, HS 1.5 seems significantly too low: a figure closer to 2 is preferable.⁴³ This view is reinforced by the specificity of Egyptian sources: most of the time, they are part of estate accounts, whereas literary evidence and administrative injunctions originating from other provinces of the Empire normally deal with local consumption prices. A sales margin or at least some transportation costs must have frequently separated prices measured on estates and local consumption centers.⁴⁴ Knowing actual transaction prices for wheat in Oxyrhynchus, Tebtunis or Karanis would suppress that source of heterogeneity. We have unfortunately no such evidence. Finally, in the case of Antioch, we must correct what is probably a typographical mistake in the Pisidian price used by Kessler and Temin. The prices provided by the Prefect’s edict are HS 2 and 2.25. The difference between a Roman price in a range of HS 5 to 6 and that in Pisidia should be HS 3.375 and not 3.13 (they meant 3.125).⁴⁵⬈#p41

The relationship we obtain with these modified data displays a slope coefficient (β) that is -0.00044 instead of -0.001, which is not surprising since moving the Pisidian, the Egyptian and Palestine prices all closer to the Roman prices brings more horizontality to the sample of variables. This is not the worst thing yet; after all, no one would care about the slope as long as it was a statistically relevant number. What actually happens is that the R², which expresses the proportion of the variance explained by the equation, dramatically falls from 79% to 10%, while the T-statistics are much too low to be statistically significant.⁴⁶ That means we cannot reject the null hypothesis, i.e., the absence of any correlation at all. In simple words, distance and prices could be irrelevant to each other.⬈#p42

At this stage, this does not mean the relationship advocated by Kessler and Temin is necessarily wrong; rather, it is essentially unstable and highly dependent on how a handful of sources are interpreted. This is particularly true of the Judean price: multiplying it by a factor of two effectively destroys the relationship. In that respect we need to keep in mind that Sperber’s work postdates by several decades Heichelheim’s contribution to T. Frank’s ESAR and that his mastery of ancient Jewish sources goes far deeper. Since changing the Judean grain price is sufficient to potentially render the equation irrelevant, we are then exactly in the same situation we described for the post-war S&P 500, where alteration in one unique parameter could kill a numerical relationship.⬈#p43

It is then a true methodological weakness to write, “We assume that the prices we observe are drawn from a distribution of prices in the early Roman Empire.”⁴⁷ The reality is that some of these prices are prices, some are testimonies, but some are uncertain reconstructions, and as such may be neither random nor normative.⬈#p44

Thus the equation supporting a market-oriented interpretation of the Roman economy could be the product of pure luck or, worse, careful data selection. The fact that challenging a single parameter leads to entirely different results, or, we should rather say, no result at all, simply means that the equation as formulated cannot be statistically upheld.⬈#p45

When Distance to Rome is not a Granted Parameter

Let us now focus on the other factor: distance to Rome. The authors, aware that land and river transportation are more expensive than sea transportation, ran their equation with and without the Po valley observation.⁴⁸ The risk taken here was not big, since that variable nearly fits with the straight line, which means that its removal was unlikely to significantly alter the coefficients. What is more surprising is the way the Lusitania parameter was incorporated. The distance used by Kessler and Temin is exactly the mileage from Madrid to Rome, as can be found on an airline website. Since ancient Romans could not fly, and Madrid is not located in Portugal, it is more relevant to use sea distances instead. The shortest seaborne itinerary between the Douro River mouth and Civitavecchia accounts for 1334 nautical miles, that is 2470 km, and not 1363 km.⁴⁹ Once that fact is introduced, the price differentials are visibly no longer aligned according to distance to Rome. The equation again becomes very weak to a point of near irrelevance, even by using the original prices as selected by Kessler and Temin.⬈#p46

Could landlocked areas trade?

Let’s examine another provenance of one of the sources used by Kessler and Temin: Antioch in Pisidia. This city is located in the Taurus range, at an altitude of 1200 m. (4000 ft.) and is separated from the sea by 200 kilometers of a hilly road, including a couple of steep climbs.⁵⁰ Using a ratio of 1: 25 for relative sea: land transport costs,⁵¹ we would translate these 200 km into the equivalent of 5000 km, next to which the 1700 km or so of sea distance would be a minor factor.⬈#p49

Reinforcing the view that Pisidian Antioch could not have been fully connected to the Mediterranean sea web is the fact the governor dealing with the grain shortage during the reign of Domitian (from which this figure derives) did not contemplate the possibility of any external help.⁵² Similarly, when Dio of Prusa had to defend himself in times of grain scarcity, he claimed that the prices then experienced by the citizens of Prusa were equivalent to the lowest prices of some other towns in the region.⁵³ Later on, Gregory of Nazianzus writes that it was impossible to import wheat to Caesarea in Cappadocia during a shortage because of high transportation costs.⁵⁴ The evidence converges on the fact that little to no price arbitration could have occurred in these landlocked areas, explaining why discrepancies between prices remained in continental provinces like Asia or Hispania.⁵⁵ High land transportation costs are certainly the main factors behind the fact that imported pottery sherds are rarely found far from coastal or fluvial areas, although this does not mean either no grain trade at all could occur.⁵⁶⬈#p50

If we now adjust the distance between Antioch and Rome to 6700 km,⁵⁷ with all remaining original data being left unchanged (Chart 3), the new equation is still quite irrelevant, with a much lower slope and a very weak R² and T-statistics: -0.00015 and 15% instead of -0.001 and 79%.⬈#p51

The following table summarizes the very weak econometric results obtained by adjusting these parameters:⬈#p52

Interim Conclusion

It could be argued that our demonstration is here circular, in the sense that we modify the parameters we know are the most likely to destroy the relationship. The reality is that the price to distance relationship is just too sensitive to any parametric mistake because there are so few observations. A high degree of caution and care is thus paramount in such a methodological approach. To assume that the ancients could fly from Madrid to Rome is simply the most obvious of a number of unfounded presuppositions that can entirely undermine the conclusions.⬈#p53

A minimal sense of rigor should then lead to the deletion of the Antioch price with a lot more justification than for the Po valley parameter, since we have as much uncertainty regarding the relative sea to land transport costs as we have for the sea to river ratio.⁵⁸ We could even go further and state that the clear absence of long distance wheat trade overland in continental Asia Minor means that any relationship between local and outside prices is simply irrelevant, or rather dependent on local agricultural conditions.⁵⁹ Then we are left with a set of 4 data points, which is really too limited to be able to draw any sort of statistically robust conclusion.⬈#p54

This is not to say prices in Rome were not generally higher than prices outside Rome. We have numerous ancient literary statements about the high cost of living in Rome. But the linearity suggested by David Kessler and Peter Temin in order to prove not only that Roman prices were high, but also that the Roman Mediterranean market was globally integrated, cannot be accepted on the basis of their simulations. We need more observations.⬈#p55

Let us travel forward in time towards early modern France in order to illustrate the potential weakness of a simple centered integration hypothesis in an economy d’Ancien Régime.⬈#p56

The Imperfect Pre-modern French Grain Market

France and England have preserved extensive records of grain prices through multiple sources, mostly in the form of records from municipalities and royal officials. Starting in the 16^th century, the mercuriales, official records of real transactions that occurred in the marketplace, started to be compiled in France.⁶⁰ Until the end of the 18^th century, they consistently display high seasonal and inter-annual variability in the same location and large discrepancies between locations relatively close to one another during the same period. The available data have to be treated with many precautions: units of measurements, even with the same name, were different from one region to another; the composition of the grain differed as well; and sometimes the exact moment at which prices were recorded is missing.⬈#p57

Chart 4 shows wheat prices measured for three different years in 31 different French cities:⁶¹⬈#p58

Paris represents the two last observations. There is some geographic consistency across time: the peaks occur in Provence and in the Alpine region. Paris is very close to the average price for each single year. Grain does not seem to travel from one region to another to take advantage of price gaps, since significant differences are witnessed even between very close locations inside the same regions.⁶²⬈#p61

Public purchases manage to alleviate some of the most serious crises, especially in Paris, but are rarely effective in smothering prices on a more regular basis. Between the moment wheat is bought, sometimes from distant locations like Poland, and its arrival, the crisis is normally over and the arrival of fresh wheat has the opposite impact of depressing prices further as local supply has been restored. This happens in 1749 in Charolais, where one year after a serious shortage, local farmers are banned from selling their new grain because of the oversupply resulting from the previous year’s orders.⁶³⬈#p62

Many cities try to store grain, but it does not seem very successful in reducing price instability either. In Strasbourg, where between half and three-quarters of the annual consumption needs are kept in storage, prices fluctuate as much as anywhere else. In 1633, Strasbourg’s granaries still include wheat officially dating from 1591, 1525 and even 1439. No doubt this is no longer consumable and points to serious shortcomings in granaries management.⁶⁴ Price controls do not work any better: as La Rochelle tries to cap the prices at which Dutch merchants may sell their products, the market simply dries up, as in Antioch a millennium before under Julian. When city councils impose maximum prices on bakers, this leads invariably to more black market transactions.⬈#p63

Interestingly, larger consumer centers are not necessarily at a disadvantage: what matters is the accessibility of additional supplies beyond local production and regular imports to match demand. In that respect, Paris is remarkably privileged, located on a large navigable river at less than 300 km from the sea coast: “A Paris, il venait du grain de partout, jusque de Naples et de Sicile.”⁶⁵ The city is more accessible from the Low Countries than from Central or South-Eastern France. As the French economist Adolphe Blanqui noted in 1843, “the villages of Castellane (in the Southern Alps region) were farther away from French influence than the Marquises Islands in French Polynesia. Communications are neither easy nor difficult: they don’t exist.”⁶⁶ As such, isolated regions may experience consistently high prices if local productivity is poor, as is the case for most of the southern half of France.⬈#p64

Eventually, discrepancies between regions seem to progressively diminish on average as we progress through the 18^th century. A better transportation network from the 1720s onward,⁶⁷ higher productivity, and increased population mobility allow a better resource allocation, well before steam boats and railways will dramatically impact these markets by opening new and more distant sources of supply outside of Europe.⬈#p65

In any case, no integrated market hypothesis can be tested successfully before the end of the century. One may argue with some reason that pre-modern France is a poor candidate for testing market efficiency: it has the most continental landmass of Western Europe; few of its rivers are easily navigable; and most do not connect the different regions together. The provinces maintained their own local fiscal system for a long time, adding tolls and duties and effectively discouraging inter-regional trade.⬈#p66

Local excise taxes were the normal practice in the Roman Empire, and even if some of its main coastal cities might have been geographically comparable to the maritime towns of North Western Europe and North America in the 18^th and 19^th centuries, where price synchronization became progressively a dominant feature,⁶⁸ we must not forget that many cities of the Empire were located inland.⬈#p67

What the French example proves is that trying to correlate prices in pre-modern economies can lead tounexpected results. If higher prices serve to locate the French capital, then Louis XIV would have been ruling France from the backwater Alpine valleys or Provence. The French evidence shows that high prices are not necessarily the privilege of a metropolis and could develop as a result of insufficient local supply in areas with limited production and communication capacities.⬈#p68

Markets, Geographic Barriers and State Intervention in the Roman World

Free integrated and efficient markets suppose an absence of significant barriers, whether geographic or institutional. Let us examine some of the patterns displayed by the Roman Empire.⬈#p69

Geographical barriers

In the Roman world, long distance trade is widely attested, as documented by the papyrus and literary evidence dealing with the Indian market, the presence of a Tyrian colony in Puteoli, of Syrians in Gaul and Asians in Italy, or legal writing dealing for instance with the cash settlement of Beirut to Brindisi trade.⁶⁹ The finding of similar ceramic types originating from specific regions all around the Mediterranean is still today the most visible witness of that network of merchants that linked together the ancient Roman world.⁷⁰⬈#p70

Whether long-distance trade would have been an efficient market is a highly disputed issue among historians. Gary Reger’s works on Delian prices led him to the conclusion that prices reported at Delos during the Hellenistic period were significantly higher than in Athens, which was doubtless a more important center of consumers. At the same time, prices of different goods like grain, oil, perfume, pitch, and papyrus seem to have followed rather different patterns, building a case against a globally integrated market in the Hellenistic Aegean world: “This result supports the argument that the modernist reconstruction of the operation of a general Greek price-setting market in the early Hellenistic period is indeed mistaken.”⁷¹⬈#p71

This does not necessarily matter very much, since Delos was a tiny island whose importance grew to a disproportionate level only when Rome decided to punish Rhodes after Pydna in 168 B.C., making it very comparable in a way to modern Singapore or Hong Kong, whose success relies heavily on specific geopolitical conditions and privileges. Similarly, diverging price-series do not necessarily mean inefficient markets: each product depends on its own supply and demand structure, whether yesterday or today. Between March 2010 and March 2011, the main commodity price indices soared by 30%. This did not prevent wheat from rising 67% and even 80% at one point, while cocoa gained only 10% and US crude oil 18%. Moreover, the conclusion that Delos’ wheat prices were in fact that high has been carefully challenged by Joshua Sosin, who concluded that a range of 4 to 7 drachmas per medimnos was certainly proper, hence dividing Gary Reger’s prices by a factor of nearly two and setting them in line with prices in Athens.⁷²⬈#p72

When focusing on more local trade, it has been argued that Egypt was most likely a relatively integrated market.⁷³ Nevertheless, price discrepancies seem to exist between regions close to one another, despite the easy connections offered by the Nile.⁷⁴ This could be the result of transportation costs and custom dues, although most trading relationships at Oxyrhynchus, for example, occurred within a short radius of about 200 km around the city, with the exception of trade with Alexandria.⁷⁵ Still seasonal prices did not move synchronically from one place to another, failing to show comparable patterns between locations separated by only a few dozens of kilometers of Nile navigation. In that respect, Peter Bang’s comparative study of Egyptian prices illustrates the limits of integration, even for neighboring wheat markets.⁷⁶⬈#p73

In inland areas, grain trading by road rarely exceeded distances of 100 km in early modern Europe, and this must have been mostly the case for the ancient world.⁷⁷ Maybe prices were quite similar across Sicily, but this was not the case within Asia or Spain.⁷⁸ When local grain markets existed, they seem to have involved producers and consumers rather than professional traders. Cicero does not speak about traders in Sicily, and the only two price-series we possess for 1^st-century A.D. Egypt show the average price achieved by some producers to be higher than that paid by consumers, leaving little room for trade-related profit.⁷⁹ Evidence for traders is scarce outside of urban environments. Nevertheless, as pointed out by Dominic Rathbone, our prices “relate almost entirely to sales in the countryside at or very near to the point of production,” and “our evidence patently under-represents large-scale transactions and the urban retail market”;⁸⁰ “corn dealers existed in Egypt.”⁸¹⬈#p74

Geographical barriers would explain why consistent regional price differences are recognized by the legal literature (Dig. 13.3.4; 13.4.3; 35.2.63.2). Isolated inland areas such as those around Pisidian Antioch, Bithynian Prusa, or Cappadocian Caesarea would have been structurally excluded from any sort of non-local market activity.⬈#p75

The availability of local surpluses

Moreover, another local factor is at play: comparing prices in various locations with those of the main consumer center (Rome) not only supposes that moving goods from one another is materially and financially possible, but also that exchangeable surpluses are always available, since prices in Rome are the determinant overall reference. If we now assume that some areas’ grain carrying capacity was inferior to the needs of their population, linking them all to one unique natural final consumer market like Rome would not reflect the reality on the ground, since more than one location would have been a net grain importer. This could easily explain why prices in Palestine are as high as in some Italian cities: the fact is that both locations might have been purchasing what they needed in grain from the same provider, i.e., Egypt. Then they can no longer be aligned with Rome, since what matters is not the distance to Rome but the distance from Egypt.⬈#p76

This can be easily plotted on a simplified simulation, where P are the Egyptian producers’ prices, M is the constant factor in the margin taken by the merchants exporting Egyptian grain, L is the unit linear cost of transportation by sea plus some proportional sales margin, Pj is the average selling price in Judaea, Pp in Pompeii for instance, D_(E-P) the Egypt – Pompeii distance, D_(E-J) the Egypt –Judaea distance,⬈#p77

Then we should have:⬈#p78

Pp = P + M + L x D_(E-P) and Pj = P + M + L x D_(E-J)⬈#p79

Implying:⬈#p80

Pp – Pj = L x (D_(E-P) - D_(E-J) ).⬈#p81

If prices in Pompeii and Judea were to be related to their distance to Rome, the following relationship would apply as per Kessler and Temin’s initial equations, where Pr is the Roman price, D_(R-P) the distance between Rome and Pompeii and D_(R-J) the distance between Rome and Judaea:⬈#p82

(Pp – Pr) = α x D_(R-P) + β and (Pj– Pr) = α x D_(R-J) + β⬈#p83

Then:⬈#p84

Pp – Pj = α x ( D_(R-P) - D_(R-J) ).⬈#p85

α is obviously equivalent to the linear distance cost factor of Kessler and Temin, with a negative sign since they work with negative numbers by subtracting the Roman price from provincial prices. Then α = - L.⬈#p86

We would get:⬈#p87

( D_(R-P) - D_(R-J) ) = - ( D_(E-P) - D_(E-J) ) or ( D_(E-P) - D_(E-J) ) = ( D_(R-J) - D_(R-P) ).⬈#p88

The only way such a relationship can be systematically satisfied is if Rome, Pompeii, Judea, and Egypt are situated on the same linear path, since both factors would then equate to D_(P-J). If one of them is not, we are dealing with a triangle that has no reason whatsoever to satisfy that relationship, as the following chart shows:⬈#p89

In essence, the assumption that some regions are net importers of grain, competing at a more modest level against Rome as a consumption center, while not being geographically aligned, implies a multipolar set of linear relationships (effectively a matricial system) that cannot mathematically lead to one single linear relationship linking all these provinces together.⁸²⬈#p91

Institutional interventions

It would be absurd to minimize the role of merchants and of markets as the normal medium of exchange and of price determination.⁸³ Even the Emperors had to deal with them to achieve their political aims.⁸⁴ If the authorities were monitoring prices, as papyri from Egypt suggest was the case until the very end of the Roman Empire,⁸⁵ “there is not one scrap of evidence to suggest that it (this monitoring) was used to intervene systematically in the market-place to compel a given level of price.”⁸⁶ We know about the alimentary schemes and official attempts at dealing with shortage situations, but they remained essentially a corrective mechanism offered to more or less willing market participants or landowners.⁸⁷ As far as free food distributions to a body of registered citizens, it neither constituted the rule across the Empire ⁸⁸ nor implied some overall control over prices, since a moderate proportion of the overall tributary grain would have been enough to provide the requested allocation to less than 200,000 citizens of Rome.⁸⁹ The Roman authorities’ isolated attempts to regulate prices ended in failures.⁹⁰ Sea merchants were so prevalent in the Roman Mediterranean that the Emperor Julian’s rhetoric goes as far as offering to a friend a property distant from the sea in order to escape from their constant solicitations!⁹¹⬈#p92

Nevertheless, institutional interventions brought obvious distortions to trade: beyond customs dues, euergetism, alimenta, and State-engineered purchases, the Roman tribute and distributive schemes must have affected production and consumption patterns in both the originating and final destination areas.⬈#p93

Rome was able to extract wealth by way of moving cash or commodities from the provinces. These two procedures would lead to opposite impacts on prices at both ends of the tributary chain: levying cash meant locals had to sell their surpluses, possibly pushing production higher, eventually removing cash from the local monetary circuit and depressing prices. The cash accumulated in Rome would locally increase the supply of money, pushing prices higher and providing an incentive for traders to bring there cheaper goods purchased in the provinces. Epigraphic and literary evidence points to cash levies in various areas of the Greek East: in Messenia, Cilicia and Syria with a 1% tax levy in cash, or in Asia proper when taxation proceeds in kind were locally sold and the money obtained this way possibly sent to Rome.⁹²⬈#p94

The opposite process involves grain levies being transported to Rome. This seems to have been occurring in Asia during the Late Republic, since publicans received custom exemptions for the transportation of the tithe to Rome.⁹³ Cicero in late Republican Sicily describes wheat levies as well. In Egypt and later in Africa, part of the grain tribute was shipped to Rome. Grain tributes are attested at various points in Roman history in Bithynia, Phrygia, Thrace, Pannonia, and Judea, while there is no strict evidence that Sicily, Sardinia, or Spain ever translated grain into a monetary tax as a matter of rule. The main grain tax, the Egyptian tribute, “can hardly have been much less than 25 or 30 million modii in most years.”⁹⁴⬈#p95

The consequence for prices is then exactly opposite: as grain is removed from the local markets, reducing its supply, provincial prices have to increase, all else being equal. At the level of the individual farmer, levying between 10 and 20% of gross production might have represented most of his available surplus, exhausting his capacity to sell grain. One might argue that Hellenistic kings and Gallic nobles may have extracted from their land as much if not more than Rome did.⁹⁵ But the difference after the Roman conquest is that a high proportion of that tribute was shipped abroad, reducing the local supplies. As most cities in provincial Roman territories grew in size, pressure to increase grain production must have been widespread and sometimes massive. Even if technological progress occurred, more marginal lands were necessarily brought under cultivation under the stimulus of higher demand, and the overall impact of the conquest must have pushed both provincial production and price levels higher.⬈#p96

In Rome proper, inflows of tax grain should have lowered local prices. A proportion of the wheat was simply offered to some categories of the resident population, and the market demand will have been reduced as a result. Levying and transporting tribute in kind to Rome must then have reduced the price differential between the provinces and Rome.⬈#p97

Sirks argued that the free distributions might not have represented more than 15% of the needs in Rome.⁹⁶ But the arrival of Egyptian, African, and Sicilian tributary wheat not only translated in terms of free grain to some segments of the population: it introduced unpaid supply through the market distribution chain.⁹⁷ In Rome, prices will then normally have been pushed lower, since the supply vs. demand equilibrium will have been shifted by the arrival on the local market of levied wheat that might not have been produced and transported to Rome at those market prices if only profit-seeking farmers and merchants had been involved.⬈#p98

Richard Duncan-Jones’ rather maximalist gross Egyptian wheat tax figure of close to 80 million modii would have been sufficient to feed one million people.⁹⁸ Whatever losses might have occurred between local usage, transport, and storage, adding the other sources of tax wheat like Africa and Sicily implies that grain belonging to the Roman authorities would have been able to feed the entire needs of the city, effectively evicting long distance private wheat trade from the Roman market if the authorities had been able or willing to directly take over the logistics of feeding the capital.⬈#p99

The existence of a structural excess in grain supply at Rome has been challenged on the basis of the frequency of grain crises in the city. There is no real contradiction here. First of all, the higher purchasing power of the Romans combined with imports of cheap staples from the provinces must have encouraged Italian farmers and landowners close enough to Rome to substitute higher margin cash crops for grain.⁹⁹ As a result, Rome became more dependent on navigation conditions. At the same time, cheap or free public grain must have helped Rome to attract more population inflows from rural areas, while the end of the conquests reduced the military attrition rate.¹⁰⁰ A significant number of veterans also returned to Italy in general and Rome in particular, while many slaves were imported into the city, pushing higher the overall population.¹⁰¹ Grain distributions had such an impact that owners freed their slaves in order to transfer the burden of feeding them to the authorities.¹⁰²⬈#p100

Moreover, one should note that in a pre-modern economy there is no contradiction between generally abundant grain supplies and the repetition of difficult years. Poor harvests, navigation conditions, and finally the great fire of 64 could explain the crises of 23 and 22 B.C. and A.D. 5, 18, 19, 32, 51 and 64.¹⁰³ Crises seem to become rare in subsequent years, maybe as a result of the huge investments undertaken in the harbor facilities of Rome by Claudius and Nero.¹⁰⁴ Nero was able to reassure the Roman population by destroying some of the surplus wheat accumulated in the Imperial warehouses, while Trajan was in a position to reduce the amount of wheat necessary to be shipped to the capital, a sign that these efforts eventually paid off.¹⁰⁵⬈#p101

All this being said, one should not overestimate the role of taxation in supplying Rome. As Jean-Michel Carrié writes: “le blé fiscal n’avait pas vocation à satisfaire la demande alimentaire de l’ensemble de la population de la capitale, mais seulement à couvrir les besoins de l’annone civique(… )”¹⁰⁶⬈#p102

The reality is that we are not told how the authorities disposed of the tax grain levied in the provinces that was surplus to the needs of the free annona of Rome and military supplies. From the price-related measures taken during the 1^st century crises by Tiberius or Nero, it is unlikely that the Imperial authorities would have been selling grain directly to the final consumers or to the bakeries, otherwise the natural course of action would have been to fix an administrative price. The emperors had to interact with merchants to alleviate food crises while not harming farmers’ and merchants’ interests.¹⁰⁷ Similarly, the incentives provided by Claudius and Nero to those who transported grain to Rome were directed at negotiatores.¹⁰⁸ As Rickman writes: “The constant stress in the literary sources of the early Empire on the importance of the corn merchants makes it likely that, ‘state corn’ or not, both the transport and the marketing of grain was very much in private hands.”¹⁰⁹⬈#p103

We have already noted how Egyptian grain could end in private hands at Puteoli, although we cannot know if this grain originated from the tax proceeds or not. The inherent weakness of the early Imperial bureaucracy compounded with these observations support the view that the proportion of the tax grain that was not given out for free or stored in the imperial warehouses was sold upstream in the distribution chain. This sale could even have taken place in Alexandria itself to agents or associates of Roman-based merchants, the cash being collected by the authorities in Rome, since the Egyptian currency had a lower metallic value. This would have been very similar to the way the socii farming the Asian tribute under the late Republic had to bid and settle their financial commitment in Rome while levying, transporting, and selling the tax wheat themselves.¹¹⁰⬈#p104

When wheat was not needed, the authorities could resort to adaeratio, i.e., levying cash instead of wheat, thereby avoiding the burden of levying, storing, and selling grain. The translation into cash would have had to take place at more or less market prices, as recorded once in 1^st century A.D. Asia.¹¹¹ This is why in the time of Cicero a market price measured in Ephesus could be used by taxpayers who wished to convert their tribute into cash instead of bearing transport costs to the coastal city.¹¹² Even if, in essence, we are not dealing with free market processes regarding tax grain, the coexistence of different processes adapted to local conditions involving some type of private transactions or at least the use of local market prices at one stage or another is quite obvious.¹¹³ In Egypt proper, the frequent purchases of wheat at fixed prices close to market prices introduced a market component in the cost factor of the wheat shipped to Rome, even if that grain was to remain public until being sold or offered at destination.¹¹⁴⬈#p105

The combination of poorly staffed bureaucracy, a high degree of autonomy for provincial authorities, difficult long distance communications, and the involvement of private merchants must then have maintained a degree of relevance for market mechanisms inside the tributary process itself, even if distorted.⬈#p106

Tax privileges

One final exogenous phenomenon has to be accounted for: by providing privileges to merchants involved with bringing grain into Rome, the Imperial authorities were altering their profit function and in consequence the market equilibrium. It is rather difficult to monetize the incentive represented by the bequest of the Roman citizenship or the exemption from the lex Papia Poppaea.¹¹⁵ But the measure taken by Nero in A.D. 58 is more numerical: the ship of a negotiator was to be deducted from one’s patrimony for tribute assessment purposes, provided he was supplying Rome with grain.¹¹⁶⬈#p107

Assuming an average carrying capacity of between 10,000 and 20,000 modii of grain, Rathbone’s calculations based on the Rhodian Sea Law of the 7^th century A.D. and different papyri reflecting rental and lease/sales costs suggest that such ships would have cost circa HS 90,000-100,000 to build.¹¹⁷ This is nearly twice the value of their wheat cargo. If we assume a typical rate of tax extraction during the Principate of 1% of property values,¹¹⁸ tribute exemption would have increased the profit margin by about 2% of the cargo value. Maybe more important was exempting from public munera those who built ships of more than 50,000 modii of capacity – or enough smaller ships of 10,000 modii to reach the same mark, as expressed by Scaevola in Dig. 50.5.3. Unsurprisingly, people were trying to get these exemptions fraudulently.¹¹⁹⬈#p108

These privileges could have contributed to mitigate the cost of ships bound to Rome with grain and oil possibly returning home empty, according to the city of Rome’s capacity to export or, better, to the other commercial opportunities offered by Africa.¹²⁰ At the same time, we are not necessarily dealing with an organized corporation of tributary grain carriers, but with a more nebulous group of ship owners and merchants who were simply carrying grain to supply the Roman people as one possible activity among others. What the authorities were doing was simply to provide an additional incentive to grain merchants and ship owners going to Rome for their private business in order to avoid disruptions and excessive price instability, reinforcing the view that a significant proportion of the tax grain might have actually been sold before being shipped to Rome. ¹²¹⬈#p109

It is unrealistic to suppose that these exemptions were only addressing the free distributed public grain. How could transportation costs of state-owned grain have been covered by the simple exemption of the tribute on the value of a ship? Even if we don’t have any actual payment receipt, the ship owners carrying the grain belonging to the State had to be directly compensated, by bidding for transportation contracts through auctions, as described by Columella.¹²²⬈#p110

The aim of these exemptions was then to provide grain merchants involved with the trade to Rome of private grain with an additional incentive on top of their existing profit margin in order to decrease the probability of a grain shortage, while the public Treasury only paid the free public grain transportation costs. We are dealing with two different compensation processes, most likely directed at the same type of intermediaries.¹²³⬈#p111

What we obtain, therefore, is a rather mixed picture, where geographic isolation, grain deficit in some areas, and a degree of public intervention that varied were interfering with market mechanisms. These factors must bring additional caution when dealing with ancient prices and their relevance to market mechanisms, although it is certainly excessive to consider that bureaucratic involvement moved effective prices very far from their natural equilibrium levels. Roman authorities tended to use traders rather than regulate them.⬈#p112

At this stage, we are able to revert to data testing. Adding new information while taking into account the different hurdles we have identified may lead to a more comprehensive picture.⬈#p113

Towards the use of More Prices

“Perhaps our analysis of these few prices will stimulate other historians to find more price pairs and to provide more evidence for or against our hypothesis.”¹²⁴⬈#p114

Indeed.⬈#p115

We have five inscriptions from Pompeii that bear on wheat prices. One of them clearly states a price of 30 asses per modius of triticum.¹²⁵ Another is open to some uncertainty as far as its reading is concerned and seems to lead towards a figure of 12 asses per modius of frumentum.¹²⁶ Two others imply a daily bread ration for slaves of 2 asses. A last graffito provides a direct price of bread, 1.5 asses per pound.¹²⁷ The key problem is to relate weight denominated bread prices to volumetric grain prices in order to be able to use 3 of these 5 numerical indications.⬈#p116

In a 2001 work, Robert Allen ran a correlation test between skilled wages, grain volumetric prices, and bread prices in 10 cities of pre-modern Europe. A formula was found, linking these prices together when denominated in grams of silver per unit according to the following formula: BREAD = 0.063 + 1.226 GRAIN + 0.017 WAGE (per day).¹²⁸⬈#p117

He applied his findings to Diocletianic prices, disregarding some major issues.¹²⁹ We know that according to the quality of the final product, extraction rates between grain and flour can differ by a wide margin. Romans did produce breads of very different qualities, and there is no guaranteed homogeneity between their practice and that of modern Europeans.¹³⁰ Another problem is to assume that Diocletianic prices are to be taken at face value: anyone studying the period knows that they were designed to undervalue the price of precious metals that were collected by the authorities through the compulsory reimbursed official purchases of gold and silver.¹³¹ Furthermore Allen’s equations include specific factors linked to each individual modern European city. These variables have a significant bearing on the results, and since no such correlation test could be run for ancient Rome due to a lack of data, any straight projection without this factor towards Antiquity creates a major level of uncertainty. Last but not least, Allen assumes an overall similarity of individuals’ relative budget structure between food, rents, clothing, and tax from Antiquity to early modern Europe that is far from certain.⬈#p118

These shortcomings can easily be demonstrated by applying the general formula to 1^st century A.D. Pompeii. We know for a fact that on at least one occasion a pound of bread cost 1.5 asses. After the Neronian reform, where 1 denarius contains about 2.8 grams of silver,¹³² this is equivalent to 0.26 g. of silver per Roman pound or 0.81 g. of silver per kilo of bread. If we use as a proxy for the salary of a skilled worker the salary of a legionary before the reform of Domitian, i.e., 225 denarii per year, the daily wage in silver terms would be about 2.1 g. assuming 300 workdays. Multiplying that factor by 0.017 as per Allen’s suggested equation provides us with a wage factor of 0.035. To this we have to add the constant factor, that is 0.063, to obtain 0.099. We just calculated the bread price per kilo to be 0.81 g. Therefore, the wage factor represents slightly over 4% and the constant factor nearly 8%, implying the sole grain component of the final bread price to be 88%, which is certainly too high. The implied result is 2.2 denarii per modius, i.e., HS 8.8, which is very high for a median price in Pompeii, 17% higher than the highest available price of CIL IV 4811 and more than twice CIL IV 1858.⬈#p119

In order to relate the cost of daily bread to a grain price, a more traditional approach is to approximate the rate of extraction between grain and flour and then the gross relationship between bread and flour prices. This is how Mrozek finds that HS 4 a modius would be a maximum for Pompeii from a daily ration of bread stated at 2 asses, assuming that a slave would consume at least 1 kilogram of wheat in the form of bread.¹³³⬈#p120

Mrozek does not state the basis of his calculation. It is most likely the work of Moritz.¹³⁴ Moritz carefully reviewed Jasny’s previous calculations derived from Pliny’s statements on bread, flour, and wheat weights and extraction rates as well as Pliny’s inconsistencies.¹³⁵ He eventually used a grain to flour extraction rate close to 60% in order to produce high quality commercial white bread. With bread weighing about 35% more than the flour used in baking it since it absorbs water, one kilo of grain would produce about 800 g. of white bread. Using a daily bread ration of c. 800 g. priced at 2 asses, the kilo of grain would cost at most 2 asses, since bread incorporates some work factor. Assuming that 1 modius weighs approximately 6.74 kilos,¹³⁶ we obtain a modius priced at most at HS 3.4, while Mrozek claimed HS 4.⬈#p121

This said, no one knows exactly the quantity of bread included in the daily slaves’ ration in Pompeii. Mrozek’s figure of c. 1 kilo of wheat is certainly based on Cato’s slaves’ monthly rations set at 4 to 4.5 modii a month for those who work in the fields.¹³⁷ This is nearly 1 kilo of wheat a day. Now Cato was only providing 3 modii a month to his higher-end slaves not involved with the hard outdoor labor. This leads to about 675 grams of wheat a day. We should assume that urban slaves in Pompeii were closer to that diet, and that they were not more poorly fed than field workers, but that their diet was certainly more diversified and pleasant. Modern studies on ancient nutrition assume daily bread requirements of c. 500-660 g. a day,¹³⁸ implying a daily grain ration of c. 700-800 g. if we assume a 1:0.8 weight relationship between grain and white bread.¹³⁹⬈#p122

If the median daily bread ration’s weight was c. 600 g. instead of 800 g., with c. 750 g. of grain being used instead of 1 kilo, since we know that the price of the daily bread ration could be 2 asses for a slave, decreasing the bread component for the same set price would push all implied maximum grain prices up by 33%. We would obtain a wheat price below HS 4.5 instead of 3.4 in Pompeii.⬈#p123

The next uncertainty lies with the quality of the bread provided to slaves. A 60% extraction ratio between bread and flour implies multiple grinding to obtain white bread and must have been reserved for high-end consumers.¹⁴⁰⬈#p124

Pliny states that military bread weighed one-third more than grain and that a modius of Balearic wheat allowed the production of 35 pounds of military bread, while all the other figures provided by Pliny are between 20 and 25 pounds per modius. Even if that 35 pounds figure is corrupt, it is clear that soldiers (and thus slaves) must have received some kind of whole wheat bread processed through a single grinding with a higher extraction rate from wheat and thus bearing a higher weight than white bread would have for the same quantity of wheat. Moritz, carefully reviewing Pliny’s figures and comparing them to more modern experiments, concludes that a flour extraction rate of 90% is likely. Thus the weight of whole wheat bread would have exceeded its incorporated wheat’s weight by about 25% instead of being lighter.¹⁴¹ This is broadly consistent with Cato the Elder providing 4 to 5 pounds of bread a day to his chain gang slaves, which is about 30 to 50% heavier than the bread extracted from the 4 to 4.5 modii of grain given to the other slaves working in the fields. If it seems clear that chained slaves digging in the vineyards needed more food than any other slave, a large proportion of that difference in weight must then derive from the low quality of the bread, heavier than the grain used to produce it.¹⁴²⬈#p125

If a lower c. 600 g. of daily bread ration of Pompeian urban slaves incorporates only 500 g. of wheat, for instance, for whole wheat bread instead of the c. 800 g. of the white wheat bread, a price of 2 asses per day for the bread ration would lead to a maximum wheat price of HS 6.75 instead of 4.5. The range would be HS 4.5 to 6.75 before incorporating any processing costs. Using a level close to 15% for the labor and profit factors would lead to a range of about HS 3.9 to 5.9 a modius with a median of HS 4.9.¹⁴³⬈#p126

Finally, we have to deal with the bread price of 1.5 asses per pound in CIL IV 4227. It can only produce a range as far as wheat price is concerned, since there is no way to determine the quality of that bread. Since one pound of bread could have incorporated as little as 0.8 pound of wheat, if whole wheat bread, and as much as 1.25 pounds of grain for high quality white bread, the implied grain price range is HS 5.3 to 8.3 after incorporating a wage and margin component of 15%.¹⁴⁴ In case we are dealing with white bread, the implied price would no longer be “plutôt élevé.”¹⁴⁵ This scenario seems likely, since a price over HS 8 in Pompeii would be quite high indeed.⬈#p127

The average of all the Pompeian prices of HS 3, 7.5, 4.9 and 5.3 per modius works out to be slightly above HS 5.⬈#p128

A daily ration of bread at 2 asses is also to be found for the cost of the bread allocated per person in a collegium at Lanuvium, 24 km south of Rome.¹⁴⁶ It is here unlikely that whole wheat bread is concerned. Rather the higher grain to bread ratio used for white bread would lead to a lower grain price close to HS 4.3, implying a price range of c. HS 4 to 5 per modius in Campania and Latium.⬈#p129

An early 2^nd-century A.D. inscription from Forum Sempronii shows wheat provided by a benefactor at a price of HS 4 in time of crisis, which could be considered as standard in assuming subsidized prices under crises to be close to prices under normal conditions.¹⁴⁷⬈#p130

Under Nerva and Trajan, alimentary schemes operated in many Italian cities: a monthly allocation of cash provided by participating landowners who had received Imperial grants was devoted to the subsistence costs of young boys and girls. Duncan-Jones assumes that three-quarters of that amount would have been used to buy 3 modii of wheat for legitimate boys, and thus relates the HS 16 a month tariff in Veleia to a modius priced at HS 4.¹⁴⁸ There are several issues with that approach. Children were not fed with wheat, but bread. With a daily bread ration set at 600 g., provided under the form of white bread, with bread occupying about two-thirds of the monthly budget with processing costs of 20%, we obtain c. HS 3.6 per modius instead.¹⁴⁹ Eventually, one may argue that using a monthly budget incorporating an unknown proportion of bread simply leads to such a wide range of possible outcomes that the indications provided by the alimenta are useless. We will still use them as an indication of a range, knowing that as such they should play a reduced role in any simulation.⬈#p131

In Terracina, in Latium, 137 km south of Rome, the alimentary scheme monthly rate was HS 20. This would lead to a modius “price” close to HS 4.5 and confirm that areas close to Rome in Latium and Campania would have witnessed higher average prices than in more backwater parts of Italy.¹⁵⁰⬈#p132

As far as non-Italian prices are concerned, we have another potential parameter, coming from Duncan-Jones’s observation that in late 2^nd century A.D. Africa, at Sicca Veneria, the alimentary scheme rates for boys and girls are between 62.5 and 66.7% of the Veleia equivalent levels. Assuming broad proportionality, the wheat price would have been close to HS 2.4.¹⁵¹⬈#p133

More thoughts on Roman Prices and Trends

Now that we have at least defined likely ranges for a certain number of additional wheat prices outside Rome, it is time to bring some last adjustments to the data assumed by Kessler and Temin and revert to the question of the prices in Rome proper. This is all the more important as what we need are not prices but price differentials with Rome.⬈#p134

Kessler and Temin have used a chronologically linear scenario, with a price increase from HS 3 to 4 in the 2^nd century B.C. to HS 5 to 6 in the 1^st century A.D.¹⁵²⬈#p135

We will start with the 1^st century A.D., since this is where some indications are available from ancient literature. Besides the low price of HS 3 briefly imposed by Nero after the great fire of A.D. 64, we do have selected indirect information regarding wheat prices during that period. There is one attested bread allocation for a 1^st century A.D. Roman collegium at 3 asses.¹⁵³ Comparing it to the collegium of Lanuvium and using a simple proportionality relationship would imply a price of HS 6.5 per modius, This is somewhat higher than the HS 5 to 6 range assumed by Kessler and Temin for the 1^st century A.D., although still in the likely variability range of ancient wheat prices.⬈#p136

The next indication is provided by Pliny’s prices for flour, between 40 and 80 asses per modius. Using the price of similago at 48 asses as the main type of flour used for processing the common bread, various authors have worked out a HS 6 to 8 range per modius of grain in Rome.¹⁵⁴⬈#p137

By analogy with the doubling in volumetric prices between raw and milled millet provided by the Price Edict of Diocletian, Duncan-Jones assumes that grain volumetric prices must be about 50% of flour prices. This is how he is able to reduce the HS 8 per modius cost computed by Jasny into HS 6 for Rome proper from Pliny’s flour price indications.⬈#p138

Using millet as a parallel to wheat is not justified: its flour extraction rate is lower, since millet is a husked grain and not wheat .¹⁵⁵ Even if Jasny’s computations may need some refinement, it is extremely difficult not to share his view that a volumetric price of HS 12 per modius of flour implies a volumetric price of wheat that can’t be much lower than HS 10 a modius.¹⁵⁶ We will therefore adjust upward the median level of 5.5 used by Kessler and Temin towards a more likely HS 7 per modius that could still be conservative.⬈#p139

The next step lies with the grain prices in Rome during the Late Republic. Since we have no direct evidence in Rome proper for that period, it is worth exploring whether or not some general rise in prices would have occurred between the Late Republic and the Early Empire.⬈#p140

Once more, Egypt provides some clues. In the later Ptolemaic period before the final debasements of the second half of the 1^st century B.C., one tetradrachm purchased between 1 and 1.5 artabas of wheat and included about 12.6 g. of silver.¹⁵⁷ After the reform of Nero, the Egyptian tetradrachm’s silver weight was about 2.5 g.¹⁵⁸ and the artaba was worth about 8 drachmas. Thus 1 g. of silver purchased 0.1 artaba under Ptolemy XII Auletes and 0.2 under Nero. Even if this may be essentially the consequence of the debasement of the Egyptian coinage between Tiberius and Nero, pushing the local purchasing power of silver artificially higher as a result, the Egyptian evidence does not point towards a general inflationary situation in the Mediterranean world between the later 1^st century B.C. and the 1^st century A.D.⬈#p141

According to a literary source dealing most probably with Spain, 4 asses seem a standard (and low) customary price for a modius of wheat for some inland isolated areas at the end of the 1^st century A.D.¹⁵⁹ This is close to the price possibly provided by Polybius for Lusitania more than two centuries before.¹⁶⁰ With Egypt, this would be a second example of overall price stability, this time between the end of the 2^nd century B.C. and the 1^st century A.D. This does not prove anything for Rome, since its newly established position as the center of the Mediterranean world may well have produced a local leap in prices during that period. Still we may question whether or not Roman prices did jump by as much as 50% between the late Republican period and Imperial times, as assumed by Kessler and Temin.⬈#p142

One clue could come from comparing the various Roman grain subsidies. The Gracchans’ scheme had provided the modius at a low price of 6.33 asses (HS 1.58) in 124 B.C.¹⁶¹ During the Empire, we have two known interventions on wheat prices during periods of hardship: one under Tiberius, where prices are fixed at some unspecified level while HS 2 per modius are given to the merchants as a recompense; later, Nero imposed a price of HS 3 after the great fire.⬈#p143

If Nero had been simply trying to enforce the price Tiberius had previously enacted, this would imply a customary HS 5 per modius during that period. Since the available information pushes towards an average prices closer to 7 at that period, Nero’s measure would actually have been more aggressive. His subsidized price would have included a discount of nearly 60%, vs 30% for Tiberius. If we assume that similar discounts were applied to the earlier Republican scheme, this would lead to a price range of HS 2.2 to 3.7 per modius in 124 B.C. This is still close to the HS 3-4 range assumed by Kessler and Temin for the mid-2^nd century B.C. If the middle of this updated range could be used as an estimate of the median price for that period, it would lead to a HS 3 level for the second half of the 2^nd century B.C. When compared to the HS 7 that seems likely during the 1^st century A.D., it would point to a more than doubling of wheat prices in Rome between the second half of the 2^nd century B.C. and the 1^st century A.D., an even more important jump than assumed by Kessler and Temin.⬈#p144

How could such a price increase over nearly 3 centuries be reconciled with the apparent stability in Egypt and Spain during most of that period?⬈#p145

First of all, the Spanish “stability” relies on very weak foundations. Martial’s “price” is a word in a poem that might have been written during a stay in Spain. These epigrams were not intended to be used in some database by “manipulators” of statistics a couple of millennia later. Furthermore we know there is a potential issue with the price for Lusitania given by Polybius through Athenaeus.¹⁶² A “Polybian” price of HS 0.25 a modius is perfectly defendable and would then imply an increase by a factor of 4 between the time of Polybius and that of Martial. However this comparison is potentially meaningless, since there is no precise geographic indication for either of these prices, and we know from Cicero that prices in Iberia differed from one location to another.¹⁶³⬈#p146

Regarding Egypt, it is worth looking more carefully into what occurs during the 2^nd century B.C., since we have previously only compared very late Ptolemaic prices to Roman prices. Interestingly, grain prices denominated in “bronze drachmas” (or rather the unit of account on which the bronze coinage was based) multiply 3-fold during a very short period of time between 150-140 and 120-100 B.C., while the price of the Egyptian silver tetradrachm in bronze drachmas remains essentially stable. The purchasing power of silver in grain is effectively divided by 3 during the second half of the 2^nd century B.C. Since the bronze coinage weight standards are divided by about the same factor by the end of that period, the relative stability of the purchasing power of bronze leads to the conclusion that silver lost about two-third of its value vs. bronze, grain and maybe other commodities at that time in Egypt.¹⁶⁴⬈#p147

The other region that provides us with price series is Babylonia, through the “Astronomical Diaries,” whose remaining tablets more or less cover the period 382 to 60 B.C. Interestingly, silver prices for all the listed commodities (Barley, Dates, Mustard, Cress, Sesame and Wool) are increased by a factor of about 3 between the years 175-150 B.C. and 100 – 75 B.C.¹⁶⁵⬈#p148

There is still another hint of a general fall of the purchasing power of silver-based currencies during the second half of the 2^nd century B.C. A retariffing from 10 to 16 asses of the denarius relationship with the bronze coinage takes place around the years 145-140 B.C. in Rome, essentially restoring a stable intrinsic relationship between both coinage since the weight of the as had been divided by a factor of 2, from 1/6^th to 1/12^th of a pound (uncial) since 211 B.C., the year the denarius was introduced.⬈#p149

After the retariffing, the weight of the as fractions drifts again lower to a de facto semuncial standard while production of the as itself comes to a near halt in 146 B.C. The restoration of the uncial standard by an obviously administrative decision in 116-115 B.C. does not last for long. By 93-92 B.C., the lex Papiria legitimizes the semuncial standard again, as if the authorities were unable to maintain the heavier bronze currency.¹⁶⁶ After a short reversion to a standard close to the uncial standard under Sulla, no significant issue of asses occurs until Augustus, who opts for the semuncial system. Since the denarius : as conversion rate remains stable, the intrinsic purchasing power of the silver contained in the denarius is effectively halved vs. the bronze between 141 and 92 B.C. In other words, the same quantity of bronze buys twice more silver through the official coinage conversion rate. The implied silver : bronze ratio has moved from c. 120 to c. 60.¹⁶⁷⬈#p150

One possible explanation would be that the Roman authorities had voluntarily increased the level of fiduciarity of the bronze coinage. That looks unconvincing: the issue of bronze coinage is very limited during the second half of the 2^nd century B.C. and most of the 1^st century B.C., unlike the first phase of debasement during the second Punic war.¹⁶⁸ Why would any monetary authority debase a currency that is barely minted? The second explanation is that the purchasing value of silver as a metal had effectively dropped between the second half of the 2^nd century B.C. and the 1^st century B.C. In that case, the Roman mint would have essentially kept the metallic value of its currency system close to its intrinsic ratio.⬈#p151

We have no hint regarding grain prices at Rome during that period except for the subsidized Gracchan scheme. Nevertheless, a division by 2 of the weight of the bronze coinage, the stability of the silver to bronze coinage ratio implying a possible drop in the value of the silver, could have led to a general doubling of most commodity prices denominated in Roman currency units during the same period. This would help to explain why political instability really worsened in Rome from the 130s B.C. onward, with a clear focus on financial measures whose aim was to alleviate the cost of purchasing food for the urban classes, through subsidized distributions of grain and land.⬈#p152

Although Egypt, Babylonia, and Rome are far apart and specific political situations may explain price rises here and there, one interesting scenario would be to postulate not a smooth doubling of most prices over nearly 3 centuries, but a general doubling in silver units of most prices all across the wider Mediterranean area during a very narrow period of time at the end of the second half of the 2^nd century B.C. In other words, a quick fall in the purchasing power of silver would have pushed all prices higher, followed by a long period of stability.⬈#p153

The key factor here could have been the increase in silver production by the Spanish mines under Roman control during the later 2^nd and early 1^st century B.C., something that would be reflected by the pace at which the Roman mints in Italy, Iberia, and Macedonia stepped up their own production of silver coinage, with a clear acceleration during the years 130-110 B.C. and a denarius peak in the 80s B.C.¹⁶⁹⬈#p154

If we retain such a hypothesis, we have to substantially increase the 1^st century B.C. Roman prices to a level closer to those of the 1^st century A.D., while creating a clear gap between them and those assumed for the 2^nd century B.C. We will therefore increase the HS 4 level used by Kessler and Temin for the time of Cicero to HS 6 and use HS 3 for the earlier period.⬈#p155

Moving forward into the 2^nd century A.D., we have only one non-Egyptian new price from Sicca Veneria in North Africa. This is a very low price of about HS 2.4 deduced from the local alimenta rate.¹⁷⁰ We need to define a likely level for the prices at Rome during that period as well to estimate a differential.⬈#p156

Since the times of Tiberius and Nero, significant monetary debasements had affected the denarius.¹⁷¹ This could have fuelled some price increase. Furthermore, the so-called Antonine plague might have had an upward impact on nominal prices as well.¹⁷² Our only other evidence for the later 2^nd century is again provided by Egyptian prices, and they did double at some point during the period 165-195.¹⁷³ At the same time, by the end of the 2^nd century A.D., the silver-debasement of the Egyptian drachma had been much more accentuated than for the denarius, leading to a loss of intrinsic relative value of about 50% compared to the mid-1^st century A.D.¹⁷⁴ Most of that relative debasement would have occurred under Commodus.¹⁷⁵ We cannot exactly evaluate the fiduciary value given by locals to their own currency during that period.¹⁷⁶ But the doubling of nominal grain prices expressed in drachmas in Egypt under Commodus could simply be related to the approximate halving of the corresponding relative content of silver vs. the denarius. In that case one may support the view that nominal grain prices elsewhere in the Empire did not follow the Egyptian rise, which would have remained confined within this province.¹⁷⁷ The very low alimenta rate at Sicca Veneria at about the same period does support that scenario.⬈#p157

We are therefore going to assume an overall broad stability for Roman prices between the 1^st and the 2^nd century A.D.⬈#p158

The Modified Equations

Before trying to visualize what these new parameters may add, let us streamline further our geographic available data:⬈#p159

• The sea distance from Alexandria to Civitavecchia is 2086 km. But the Fayyum is located at about 350 km from the sea by canals and the Nile. Using a 1: 5 sea: river factor to obtain a weighted distance, the rounded figure becomes 3700 km.¹⁷⁸
• From Ascalon to Civitavecchia, the distance is 2437 km, rounded to 2440. We need not add any land transportation factor, since the most fertile area of Palestine is the coastal plain.
• For the Po Valley, from Venice to Civitavecchia, we have 1742 km. We will add a weighted 500 km for 100 km of downstream Po navigation,₁₇₉ leading to 2250 km.
• We have been using Civitavecchia instead of Ostia or Portus in order to get modern easily verifiable distances. We similarly have not taken into account the Tiber upward journey. Since this fixed difference is added to all prices, it won’t change any relationship. But one figure needs some adjustment: Lanuvium, very close to Rome by land. Instead of adding a fixed factor to every other numbers, we decrease its weighted distance to Rome by 27 km of river journey, equivalent to 135 km by sea.
• Forum Sempronii lies 278 km away from Rome, through the Apennines, the equivalent of 6,950 km by sea if we multiply the initial figure by 25 to translate it into comparable sea distance in cost terms. An alternative to the overland route to Rome would have been to carry goods to the coast and ship them by sea. The city (modern Fossombrone) was 30 km away from the coast and was linked by the Via Flaminia to a harbour named Fanum Fortunae, re-founded in 49 B.C. by Julius Caesar, and later a colony under Augustus. Taking into account 1600 km of sea distance to modern Civitavecchia through the straits of Messina, we obtain a more competitive weighted 2,350 km. However, if the harbor facilities at Fanum Fortunae were inadequate, the next nearest harbor, Ancona is situated 95 km by road from Forum Sempronii, and the weighted adjusted figure from Rome becomes 4000 km. This is a huge difference and shows how econometrics are sensitive to assumptions about the way the ancient economy was operating. We will prefer the first number: Fanum Fortunae was a significant city,¹⁸⁰ with a natural harbor still restored by pope Paul V in the early 17^th century.
• Terracina is located on the via Appia and more importantly is a coastal city located half way between the cities of Campania and Ostia. There was a small harbor, renovated under Trajan and Antonius Pius, 137 km from the Tiber estuary.
• Sicca Veneria is located inland, at 92 km from the closest seaport, Thabraca, where the distance to Civitavecchia is 600 km, leading to a weighted 2900 km for the entire journey. ¹⁸¹
• Veleia is located about 30 km south east of Placentia; the latter was 40 Roman miles south of Milan on the road to Rome, itself 433 Roman miles away from Rome.¹⁸² The distance from Veleia to Rome is therefore close to 550 km, equivalent to 13,750 km by sea (!). A less expensive journey would use the 78 km of road linking Veleia to Luna, on the Via Aurelia and close to modern La Spezia, and then the 182 nautical miles to Civitavechia. The overall sea-weighted distance would be 2262 km.

We have now expanded the initial database from 6 to 12 factors, leading to potentially more stable results, notwithstanding the intrinsic weaknesses and uncertainties of these numbers.⬈#p160

It is graphically obvious that the results will show a lower level of correlation when using the entire sample. We will therefore run two tests: first with these 12 data, and second by restricting a final sample to the broad Egypt-Rome trade axis, into which we incorporate Sicily and Africa.⬈#p163

If we now graphically plot the highest quality regression line from the most reduced sample we obtain the following chart:⬈#p164

The conclusions are quite straightforward. First of all, the linear relationship is much weaker when taking into account all available prices. The level of 79% of the variances obtained by Kessler and Temin is reached or overtaken only by careful sample selection limited to Rome, Latium, Campania, Sicily, Africa, and Egypt. The overall dataset leads to 56% of the variance being incorporated by the closest possible line. That should not come as a surprise and materializes the fact some of these locations had little to none long distance grain trading relationship. It of interest to note that similar results are achieved when numbers are drawn from the Standford University ORBIS Project (http://orbis.stanford.edu/), which appeared after the above calculations were complete.⬈#p167

This would support the view of quite a dichotomous ancient Roman economy, where consuming and producing regions accessible by sea trade could display truly efficient price behavior, while areas left outside the main trade axes would live an economic life essentially driven by local considerations, at least as far as an essential staple like grain is concerned.⬈#p168

There remains one final issue that has not been addressed so far: the high prices recorded in the Greek world.⬈#p169

The limits of the Rome-centered model

Aegean wheat would have sold at standard prices no higher than 5 to 7 drachmas per medimnos during the Hellenistic period.¹⁸³ This would translate into an average close to 1 Roman denarius or 4 sestertii per modius. Although we possess no regular Roman prices for that period, it seems likely that they were lower. After the extremely high prices experienced during the second Punic war, we are told that 4 asses (= 0.4 denarius) and then 2 asses a modius were abnormally low in 203 and 202 B.C.¹⁸⁴ A little less than a century later, 6.33 asses (= 0.4 denarius still since the retariffing had taken place) is a subsidized price. Such indications would not easily be compatible with customary prices close or higher than 16 asses, although we have no firm evidence. Still, it seems likely that prices in some if not most Hellenistic metropolis were higher than prices in Rome under the Republic.⬈#p170

Notwithstanding the impact of the Roman conquest of the East, later imperial evidence points in the same direction: the main cities of the Aegean area remained very expensive throughout the Hellenistic and Roman periods compared to Western prices.⬈#p171

In Ephesus at the time of Trajan, prices of bread were regulated by the local authorities at an average levels of 2 obols per pound for the standard quality.¹⁸⁵ Naum Jasny’s calculations point to a grain price ten times higher than in Antioch in Pisidia, to a point where the author is so surprised by the gap that his conclusion is “not to use the evidence for Asia Minor in that study.”¹⁸⁶ After translating his prices in cents per bushel or British pounds back into ancient units, this is equivalent to HS 19.9 per modius.¹⁸⁷⬈#p172

However, Jasny does not pay any attention to the peculiarity of the monetary system of Roman Asia during the High Empire. The term obol should normally refer to the subdivision of the regional currency that was minted with a reduced weight standard, the cistophoric drachma, valued at 12 Roman asses. That local tetradrachm was thus worth 3 denarii instead of 4.¹⁸⁸ Then 1 obol is worth 2 Roman asses and not 2.67, and the denarius 8 obols. In order to ensure some symmetry with its own system, a local as, the assarion, whose value was 16 to 18 to the denarius, was introduced.¹⁸⁹ Jasny’s price of HS 19.9 should therefore be corrected into HS 14.9 per modius. For Rome, our computations led to a median price of HS 7 vs. Jasny’s HS 8. Applying the same proportionality would lead to HS 13 per modius in Ephesus.⬈#p173

Another approach could refer to the bread price of 1.5 asses per pound in Pompeii. We had previously computed from this price a grain price range of HS 3.6 to 5.1 per modius. Applying the same method for Ephesus with 2 obols = 4 asses would imply a HS 9.6 to 13.6 range. Since we know here the bread is here of the lower quality (another price is provided for fine bread: 3 obols for 9 ounces), we know we have to use the higher price. This is very close to Jasny’s findings, and it would seem safe to assume that Ephesus’s wheat prices were significantly higher than in Rome by a margin of maybe up to HS 5-6 per modius.⬈#p174

The main issue with these estimations is the uncertainty surrounding the true value of the local obol once translated in Roman Imperial currency terms. In classic Greece, the most widespread relationship follows the Attic standard: 6 obols to 1 Attic drachma. At that time, the obols were small silver coins approximately weighing 1/6^th of a silver drachma, or, better, 1/24^th of a tetradrachm. Since the Attic drachma equals a denarius, and the cistophoric tetradrachm 3 denarii, this is how we related 1 obol to 2 assaria or 1/8^th of a denarius. When Greek states started to mint bronze coins, that relationship was maintained, even though the bronze coinage was effectively overvalued, since its intrinsic value in bronze was lower than the value as indicated by its rate of exchange with the silver coins.¹⁹⁰⬈#p175

Things are no longer that straightforward during the Hellenistic period: token coinages need a high degree of trust to operate. In 2^nd century B.C. Egypt, the bronze drachma became a unit of account most likely defined following the formula 10 “new” drachmas = 1 “old” obol.¹⁹¹ Something quite similar occurred in Athens after it submitted to Sulla. A heavily overvalued bronze drachma of less than 10 g. was minted, and it seems obvious it was not accepted at face value outside of Athens. After a gap of more than a century, Athens started to mint the same bronze modules again under Hadrian. Then we know from a contemporary inscription in the Agora that 1 bronze drachma was worth not 1 denarius, but 1/6^th of a denarius, while a later 2^nd century religious law mixes denarii with leptû drachmas¹⁹²⬈#p176

This phenomenon could have been peculiar to Athens or widespread. The reality is that we are very often not in a position to opt for one scenario or another, since Greek coinage normally bore no marks of value.¹⁹³ In the 2^nd century A.D., Aeginus in the Peloponnesus struck coins marked hemiobols weighing c. 8 g., showing that city had not adopted the debased Athenian system but had stuck to the old standards.¹⁹⁴⬈#p177

We have reasons to think Athens was not an isolated case and that Ephesus was most likely operating with a similar standard during the Imperial period. Under Trajan, Rhodes struck large bronze coins weighing about 20 g. and marked didrachmon, metrologically quite consistent with the contemporary Athenian coinage.¹⁹⁵⬈#p178

In Asia Minor, Roman denominations appear on the epigraphic material from Tiberius onward with the Sagalassus inscription, denarii and assaria being often mixed with Greek numerals, drachmas, obols and chalkia. The Trajanic Salutaris inscription in Ephesus as well as the Hadrianic banking regulatory text of Pergamum use denarii and/or assaria, while the tetrachalkia appear under the Flavians. Several other inscriptions from Asia Minor testify to the wide use of the assarion, while obols fade away with the 2^nd century. In the 3^rd century A.D. at the latest, ancient Greek denominations are absent from the Asia Minor numismatic material. Coins minted in Pergamum of c. 8 and 4 g. in the 2^nd century would have been assaria and half-assaria. In Chios, which had struck assaria since the early 1^st century A.D. and was the only Greek city to often indicate marks of values, the last appearance of the obol occurs under Hadrian.¹⁹⁶⬈#p179

The pricing in obols in 2^nd and 3^rd century A.D. Ephesus is thus somehow anachronistic, unless we are again dealing with a different unit of account. This could be possibly implied by a dossier of Hadrianic inscriptions from 124 and 125 A.D. where denarii and assaria are the normal units of accounts, with the exception of one amount expressed as 300 drachmas: one wonders why both units would be used unless we are dealing with two different units of reckoning.¹⁹⁷ Interestingly, the unique example of the use of the phrase “silver assaria,” obviously referring to a unit of account since there were no silver assaria coins, is to be found in an inscription from early 2^nd century A.D. Ephesus, pointing to the fact that silver and bronze likely belonged to two different systems of denomination.¹⁹⁸⬈#p180

If Ephesus and some other Eastern Greek cities had been following Athens and Rhodes in establishing the drachma and obol as fractional units of account of the denarius, the available bread price would have to be translated at an entirely different rate. In Athens, the bronze “drachma” had replaced the old obol, and the new obol had become 1/36^th of a denarius. A similar division by a factor 6 would lead to a denarius being worth 48 new obols since the local silver drachma is lighter by a quarter compared to the silver Attic standard.⬈#p181

In this case, 2 obols a pound for whole wheat bread means 1/24^th of a denarius per pound, and 3 obols for 0.75 pound of white bread leads to 1/12^th of a denarius per pound. As per the calculations for Pompeii, assuming respectively a 0.8 to 1.25 wheat to bread ratio according to its quality leads to a HS 4.4 to 5.6 range. We will then use HS 5 as an estimate compatible with both prices. This is very different from the previous estimate close to HS 14. This wide level of uncertainty entirely relies on what unit of account the obol is referring to in Hadrianic Ephesus. We believe the lower scenario is better supported by the epigraphic and numismatic analysis.⬈#p182

We have a few more testimonies from Imperial Greece and Asia at times of scarcities. In Sparta, under Hadrian, a grain official provides grain at 1 denarius per hemiekton, i.e., HS 8 per modius, while prices had reached 40 denarii per medimnos (HS 26.67 per modius). At Sebastopolis in Caria in the late 2^nd century A.D., a city located inland at about 50 km from the Meander valley, wheat is sold by a private benefactor at 2 denarii per kupros, i.e., HS 4 per modius.¹⁹⁹ If subsidized prices bear a close relationship to standard market prices,²⁰⁰ these figures fit rather well within the Italian price range.⬈#p183

Next comes Alexandria proper. Although we do not have any price information regarding wheat transactions during the Roman period, there is at least some hint with respect to the price structure in Ptolemaic Egypt. In a year close to 270 B.C., a set of sales accounts concerning wheat being transported from the Herakleopolite nome to Alexandria involves a very high price of 4 drachmas, 5 obols per artaba, whereas the Egyptian average price at that time was 2 drachmas per artaba.²⁰¹ Although this sale is not specifically reported to have occurred in Alexandria, the situation described by the papyrus and the price itself point towards such a hypothesis. The implied countryside to Alexandria ratio is about 1:2.4.⬈#p184

That looks certainly too high, since the same papyrus shows barley selling only one third above standard country prices, leading to a very unusual ratio of 1:3 between barley and wheat here, compared with the usual range of 1:1.5 to 1:2. So maybe some temporary disturbance produced that price of wheat out of line with normal. This could suggest that a more normal Alexandrian wheat price was somewhere between 2.5 and 3 drachmas at this period.²⁰²⬈#p185

Applying such a price structure to Roman Egypt, Alexandria wheat prices would have been close to HS 2.75-3 per modius, with countryside prices of about HS 2. The absence of any evidence for the Roman period will prevent us from trying to use that estimation as the price of wheat in Alexandria.⬈#p186

After computing the distances to Rome, the new chart obtained by adding the additional Eastern locations shows as expected a less linear and as such a less integrated result.⬈#p187

The picture that emerges is of a more multipolar economy, where a main trade axis does show up between some coastal regions aligned on a broad Egyptian-Italian axis, while other areas do not fit into any linear relationship with Rome.⬈#p190

Greece and coastal Asia Minor are two of the wealthiest regions of the Empire from the late 1^st century A.D. onward. As during the time of the Athenian Empire, the area relied on some external grain in order to sustain itself. In periods of shortage, we have evidence of Egyptian wheat imports, although there is no consensus about how casual they were and how restrictive the Imperial authorities were about them.²⁰³ We might keep some doubts about the significant character of the Spartan price, as it seems very high compared to the overall regional average, and that further highlights the fact benefactors might have been in a position to take some profits in selling their reserves at times of scarcity.⬈#p191

The Greek East case is actually similar to what we concluded for Palestine: little to no grain surplus, no direct relationship with Rome, not located on the Roman grain route, rather a competing position as a grain import centre.⬈#p192

Towards Partial Grain Market Integration

What does this tell us? First and foremost, the proportion of grain import vs. local production must have been marginal in most locations of the Empire. As we reflected for Antioch in Pisidia, Prusa, or even cities like Forum Sempronii, the relative value of wheat vs. its weight made it an unlikely candidate for profitable trade. Hence local conditions must have been generally the main factors in explaining the equilibrium price of grain in a given location, or at least played a significant role.⬈#p193

This does not mean that cities in some regions did not tend to develop some common pattern. Italian prices seem pretty much alike, prices being higher in coastal areas and closer to Rome than inside the peninsula. Asia Minor seems to show something of a regional pattern as well: the 3 locations we have information about are graphically rather well aligned. Since their sea distance to Rome is about the same, what matters in that case is their weighted distance to the coast. This would somehow bring some additional information to Cicero’s statement that prices inside the provinces of Asia (and Iberia) could vary, unlike the relative uniformity that would have characterized Sicily: they would vary according to their distance to the coast, and this confirms Cicero’s statement about Ephesus’ prices compared to inland Philomelion.²⁰⁴⬈#p194

Does this mean that inland cities could have been directly trading grain with each other? Veleia and Forum Sempronii, or Sebastopolis and Antioch in Pisidia, certainly did not. Nevertheless, a minimum level of capillarity in short-distance land transportation of grain and human mobility itself must have linked adjacent regions, eventually creating mechanisms by which average prices in normal years could not move too far from one another within each province of the Empire. Such a scenario would find another confirmation for the Balkans and Asia Minor, where coastal cities’ hoards show bronze coins minted far away in significant proportions, whereas isolated inland locations display a more local circulation patterns.²⁰⁵ This is quite consistent with the higher coastal prices vs. the interior that we are highlighting for this region.⬈#p195

Still, the broad comparability of prices in distant areas like Ciceronian Sicily or Pisidian Antioch leads Jean Andreau to suggest that: “(…) toute identité de prix ne révèle pas un phénomène de «marché» (…). Si les conditions de production et le rapport entre l’offre locale et la demande locale sont identiques, le prix peut aussi être identique, sans qu’il existe aucun contact entre les lieux concernés.”²⁰⁶⬈#p196

One could question whether more fundamental integrating factors would not have been in play too. Prices in isolated areas might eventually have become broadly aligned with many other areas of the Empire, since migrations and access to the same monetary system and broader cash pool would tend to cap divergences within a single overall continuous price structure. In essence, poorly productive areas would experience population losses through emigration until their supply to demand balance was restored, and vice versa.⬈#p197

That said, maritime areas of the Empire developed some integrated economic patterns as far as the grain trade is concerned: the high linearity of the cities located on the Rome-Sicily-Africa-Egypt axis cannot be dismissed out of hand, while, at a regional level, what seems to matter most is the distance to the coastline.⬈#p198

Another interesting problem is the evolution of the likely price ratio between Egypt and the Aegean world from the Ptolemaic into the Roman period. Since the Aegean average wheat price seems to have been close to 1 denarius per modius during the first two centuries of the Empire, its relative ratio compared to Egyptian domestic prices of about 8 to 12 local drachmas per artaba would have been close to 2 at the official currency exchange rate of 4 Egyptian drachmas per Roman denarius.²⁰⁷⬈#p199

During most of the Hellenistic period, the average Aegean price had been around 5 to 7 Attic drachmas per medimnos, i.e. 1 drachma per modius.²⁰⁸ These prices are mostly from the 3^rd century B.C. and the first half of the 2^nd century. During that period, Egyptian wheat prices in silver currency terms were close to 2 Ptolemaic drachmas per artaba.²⁰⁹ Provided the Egyptian kings managed to consistently impose an overvalued parity exchange rate towards the Attic standard, that leads to Egyptian prices of about 45% of the Aegean average.²¹⁰⬈#p200

The cumulative uncertainties of the data and the fact they don’t concern the same Aegean locations don’t allow for a more accurate comparison. Nevertheless, if that order of magnitude were correct, such stability between Hellenistic and Roman ratios would highlight the surprisingly minor impact on the Eastern wheat price structure of the Roman tributary process. Most likely some production increase large enough to stand the impact of the city of Rome’s supply requirements must have happened in various parts of the Roman world, Egypt included.²¹¹ That the Empire was later able to set up a new capital in Constantinople, diverting grain flows from Rome as a consequence, tells us a lot about the most likely production increase that took place in many areas of the West and the East.²¹²⬈#p201

To that extent, the Rome-Sicily-Africa-Egypt commercial axis within a generally more fragmented economic “Roman” world did not develop at the visible expense of the other areas. The dividends of the Roman peace would have globally financed the tributary extraction.⬈#p202

Rather than an integrated single market for grain, the Empire would have been a combination of partially integrated regional or local markets, where the distance to the coastline would have been the main factor, while a major sea-trade axis linking the most productive areas to the most demanding consuming center would have emerged. As far as the role of the State is concerned, rather than by becoming a trading actor itself, it would have contributed to displace the market equilibrium towards a more politically desirable outcome by a combination of incentives and restrictions that would have been more effective than commonly thought.⬈#p205

Public intervention did not exclude traders and markets from the equation. On the contrary, Rome proved materially unable or culturally unwilling to set up a State-run centralized economy. But any equilibrium that the Roman world reached was a combination of the activity of profit-oriented individuals evolving within a more global framework of an Imperial policy aware of the basic economics on which its very existence relied upon.²¹³⬈#p206

Conclusion: Modern Methodologies and Ancient Societies

Historians should be grateful for the intrusion of numerical analysis into ancient history. The efforts by Peter Temin to scientifically use ancient “numbers” tell us that such approaches, used with the proper caution, care and methodology, do offer a degree of leverage in helping to understand ancient economies better. Still, it seems to us that the ancient Mediterranean grain market is a difficult environment in which to test the use of numerical analysis. The very limited number of available data along with their level of uncertainty does not lead to very stable results. Any new price discovery could potentially modify all these findings.⬈#p207

Focusing on Egypt as a single province or shifting our attention towards the later Empire could prove promising, however: there are many papyri in the first case, while moving into a later period could partially complete or contradict the present results.⬈#p208

That said, it seems difficult to dismiss the fact the Roman economy did display a certain degree of market integration, particularly alongside some sea trade routes. Economically, the Roman Empire was the true produce of the Mediterranean Sea.⬈#p209

Economics did not start with Adam Smith. The man who wrote: “And the best and greatest art is the art of government which causes the good deep soil in lowlands and highlands to be tilled, and all the seas to be safely navigated by merchantships laden with cargoes to effect the exchange of goods which the countries in desire for fellowship render each other, receiving those what they lack and sending in return those of which they carry a surplus” is indeed not David Ricardo, but Philo of Alexandria.²¹⁴⬈#p210

Works Cited

Allen 2001: Allen, R. C. 2001. “The Great Divergence in European Wages and Prices from the Middle Age to the First World War,” Explorations in Economic History 38, 411-447.⬈#work_cited1

Allen 2007: Allen, R. C. 2007. “How prosperous were the Romans? Evidence from Diocletian’s Price Edict (301 AD),” University of Oxford, Department of Economics, Discussion Papers Series 363. ⬈#work_cited2

Alston 2005: Alston, R. 2005. “Trade and the City in Roman Egypt,” in H. Parkins and C. Smith (eds.) Trade, Traders and the Ancient City (London), 168-202.⬈#work_cited3

Andreau 1994: Andreau, J. 1994. “Pompéi et le ravitaillement en blé et autres produits de l’agriculture (I^er siècle ap. J.-C.)” in Centre Jean Berard. Le ravitaillement en blé de Rome et des centres urbains des débuts de la République jusqu’au Haut Empire, actes du colloque international de Naples, 1991 (Naples-Rome), 129-136.⬈#work_cited4

Andreau 2007: Andreau, J. 2007. “ Le Prix du blé en Sicile et à Antioche de Pisidie” in J. Dubouloz and S. Pitta (eds.), La Sicile de Cicéron, Lectures des Verrines (Besançon), 111-125.⬈#work_cited5

Andreau et al. 2008: Andreau, J., G. Carré, J.-M. Carrié,  and C. Lamouroux. “ La fiduciarité des monnaies métalliques: une comparaison historique” in B. Théret (ed.) La monnaie dévoilée par ses crises (Paris), 281-284.⬈#work_cited6

Arbellot 1973: Arbellot, G. 1973. “La grande mutation des routes de France au XVIIIè siècle, in Annales, Economie, Sociétés,” Civilisations 28, 765-791.⬈#work_cited7

Arnaud 2008: Arnaud, P. 2008. “L’Afrique dans le chapitre XXXV de l’Edit du Maximum de Dioclétien” in J.M. Candau Morón, J. F. González Ponce and A.L. Cháves Reino (eds.) Libyae Lustrare Extrema. Realidad y literatura en la vision grecorromana de África. Homenaje al Prof. Jehan Desanges (Salamanca), 127-144.⬈#work_cited8

D’Avenel 1910-1914: D’Avenel, G. 1910-1914. Histoire économique de la propriété, des salaires, des denrées et de tous les prix en général depuis l’an 1200 jusqu’en l’an 1800 (Paris).⬈#work_cited9

Bagnall 1977: Bagnall, R.S. 1977. "Bullion Purchases and Landholding in the Fourth Century," Cd'E 52 , 322-36.⬈#work_cited10

Bagnall 1985: Bagnall, R.S. 1985. “Currency and Inflation in Fourth Century Egypt,” BASP sup. 5, 5.⬈#work_cited11

Bagnall 1989: Bagnall, R.S. 1989. “Fourth-Century Prices: New Evidence and Further Thoughts,” ZPE 76, 69-76.⬈#work_cited12

Bagnall 1993: Bagnall, R.S. 1993. Egypt in Late Antiquity (Princeton).⬈#work_cited13

Bagnall 2000: Bagnall, R.S. 2000. “Production and Public Powers in Antiquity,” CPS sup. 26, 86-91.⬈#work_cited14

Bagnall 2002: Bagnall, R.S. 2002. “The effects of plague: models and evidence,” JRA 15, 114-120.⬈#work_cited15

Bagnall 2009: Bagnall, R.S. 2009. “Geography, Measures, Currency, Names, Prosopography, and technical Vocabulary,” in R.S. Bagnall (ed.) The Oxford Handbook of Papyrology (Oxford), 179-196.⬈#work_cited16

Bagnall and Worp 1980: Bagnall, R.S and K.A. Worp. 1980. “Grain land in the Oxyrhynchite nome,” ZPE 37, 263-264.⬈#work_cited17

Bang 2008: Bang, P.F. 2008. Imperial Bazaar: A Comparative Study of Trade and Markets in a Tributary Empire (Cambridge).⬈#work_cited18

Bes and Poblome 2009: Bes, P. and J. Poblome, 2009. “African Red Slip Ware on the move: the effect of Bonifay’s Études for the Roman East” in Humphrey, J. H. (ed.) Studies on Roman pottery of the provinces of Africa Proconsularis and Byzacena (Tunisia). Hommage à Michel Bonifay (Portsmouth), 73-92. ⬈#work_cited19

Bolin 1958: Bolin, S. 1958. State and Currency in the Roman Empire to 300 A. D. (Stockholm).⬈#work_cited20

Boatwright 2000: Boatwright, M.T. 2000. Hadrian and the Cities of the Roman Empire (Princeton).⬈#work_cited21

Bransbourg 2010: Bransbourg, G. 2010. Fiscalité et enjeux de pouvoir dans le monde romain, PhD thesis, EHESS, Paris (unpublished).⬈#work_cited22

Braudel 1979: Braudel, F. 1979. Civilisation matérielle, Economie et Capitalisme, XV ^e– XVIII^e Siècle, tome 3, Le Temps du Monde (Paris).⬈#work_cited23

Breglia 1950: Breglia, Laura. 1950. “ Circolazione monetale ed aspetti di vita economica a Pompei” in Amedeo Mauri (ed.) Pompeiana. Raccolta di studi per il secondo centenario degli scavi di Pompei, (Naples), 41-59.⬈#work_cited24

British Museum: British Museum Department of Greek and Roman Antiquities. Newton, C.T. (ed.) 1874.  The Collections of Ancient Greek Inscriptions in the British Museum III (London).⬈#work_cited25

Brougthon 1940: Brougthon, T. R. S. 1940. “Roman Asia Minor,” ESAR V, 879-880.

Brunt 1971: Brunt, P.A. 1971. Italian Manpower, 225 B. C. – A. D. 14 (Oxford).

Burnett et al. 1992: Burnett, A., M. Amandry, and P. Pau Ripollès 1992. Roman Provincial Coinage I (London & Paris).

Butcher and Ponting 2005a: Butcher, K. and M. J. Ponting. 2005. “The Egyptian Billon Tetradrachm under the Julio-Claudian Emperors,” SNR 84, 93-124.

Butcher and Ponting 2005b: Butcher, K. and M. J. Ponting 2005. “The Roman denarius under the Julio-Claudian emperors: mints, metallurgy and technology,” OJA 24.2, 163-197.

Buttrey 1957: Buttrey, T.V. 1957. “On the Retariffing of the Roman Denarius,” ANS, Mus. Notes 7, 57-65.

Buttrey 1993 Buttrey, T.V. 1993. “Calculating Ancient Coin Production: Facts and Fantasies” in Numismatic Chronicle 153, 335-351.

Cadell and Le Rider 1997: Cadell, H. and G. Le Rider. 1997. Prix du blé et numéraire dans l’Egypte Lagide de 305 à 173 (Brussels).

Caley 1958: Caley, E. E. 1958. “Chemical Composition of Alexandrian Tetradrachms” in Harold Ingholt (ed.), Publication of the American Numismatic Society (New York), 167-180.

de Callataÿ 1997: de Callataÿ, F. 2011. “Quelques estimations relatives aux nombres de monnaies grecques: les collections publiques et privées, le commerce et les trésors.” Revue Belge de Numismatique 143, 21-94.

de Callataÿ 2011: de Callataÿ, F. 2011. “Quantifying Money Production in Greco-Roman Times: a general frame” in F. Callataÿ (ed.) Quantifying Monetary Supplies in Greco-Roman Times  (Bari), 7-29.

Camodeca 1999: Camodeca, G. 1999. Tabulae pompeianae Sulpiciorum. Edizione critica dell’Archivio puteolano dei Sulpicii (Rome).

Carri é 1975: Carrié, J.-M. 1975. “Les distributions alimentaires dans les cités de l’empire romain Tardif,” MEFRA 87.2, 995-1101.

Carrié 1988: Carrié, J.-M. 1988. “Observations sur la fiscalité du IV^e siècle pour servir à l’histoire monétaire ,” in L’;«Inflazione» nel quarto secolo d.C., Atti dell’incontro di studio(Rome).

Carri é 1994: Carrié, J.-M. 1994. “Les échanges commerciaux et l’Etat antique tardif” in

J. Andreau, P. Briant and A. Descat (eds.) Les échanges dans l'Antiquité: le rôle de l'état (Saint-Bertrand-des-Comminges), 115-154.

Carrié 2003: Carrié, J.-M. 2003. “L’institution annonaire de la première à la deuxième Rome: continuité et innovation” in B. Marin and C. Virlouvet (eds.), Nourrir les cités de Méditerranée, Antiquité – Temps modernes (Paris), 153-212.

Carri é  and Rouselle 1999: Carrié, J.-M. and A. Rouselle. 1999. L’Empire romain en mutation, des Sévères à Constantin (Paris).

Casson 1980: Casson, L. 1980. “The Role of the State in Rome’s Grain Trade” in J.-H. d’Arms, E. C. Kopff  (eds.) The Seaborne Commerce of Ancient Rome: Studies in Archaeology and History. MAAR 36, 21-33.

Cavagna 2010: Cavagna, A. 2010. La Crisis dello Strato Tolemaico tra Inflazione e Svalutazione del Denaro (Milan).

Chant and Goodman 1999: Chant, C. and D.C Goodman.1999. The Pre-Industrial Cities and Technology Reader: Cities and Technology (Abingdon).

Ciarallo 1994: Ciarallo ,A. 1994. “Il frumento nell’area vesuviana” in Le ravitaillement en blé, 137-139.

Cottier et al. 2008: M. Cottier, M. H. Crawford, C. V. Crowther, J.-L. Ferrary, B. M. Levick, O. Salomies and M. Wörrle (eds.) The Custom Law of Asia (Oxford).

Crawford 1974: Crawford, M. 1974. Roman Republican Coinage (Cambridge).

Crawford 1985: Crawford, M. 1985. Coinage and Money under the Roman Republic: Italy and the Mediterranean Economy (Berkeley and Los Angeles).

Christiansen 1987: Christiansen, E. 1987. The Roman Coins of Alexandria. Quantitative Studies. Nero, Trajan, Septimius Severus (Aarhus).

De Vries and Van der Woude 1997: De Vries, J. and Ad Van der Would. 1997. The First Modern Economy: Success, Failure, and Perseverance of the Dutch Economy, 1500-1815 (Cambridge).

Diehl 1910: Diehl, Ernest, 1910. Pompeianische Wandinschriften und Verwandtes, (Bonn).

Domergue 2008: Domergue, C. 2008. Les Mines Antiques, La production des métaux aux époques grecques et romaines (Paris).

Drexhage 1991: Drexhage, H.-J. 1991. Preise , Mieten/Pachten, Kosten und Löhne im römischen Ägypten bis zum Regierungsantritt Diokletians  (St. Katharinen).

Duncan-Jones 1974: Duncan-Jones, R. 1974. The Economy of the Roman Empire (Cambridge).

Duncan-Jones 1976a: Duncan-Jones, R. 1976. “The Price of Wheat in Roman Egypt,” CHIRON 6, 241-262.

Duncan-Jones 1976b: Duncan-Jones, R. 1976. “The Choenix, the Artaba, and the Modius,” ZPE 21, 43-52.

Duncan-Jones 1990: Duncan-Jones, R.1990. Structure and Scale of the Roman Economy (Cambridge).

Duncan-Jones 1994: Duncan-Jones, R. 1994. Money and Government in the Roman Empire (Cambridge).

Erdkamp 2005: Erdkamp, P. 2005. The Grain Market in the Roman Empire: A social, political and economic study (Cambridge).

ESAR: Frank, T. (ed.) 1933-1940. An Economic Survey of Ancient Rome (Baltimore)

Faucher and Lorber 2010: Faucher, T. and C. Lorber, “Bronze Coinage of Ptolemaic Egypt in the Second Century BC”, AJN Second Series 22 (2010), 35-80.

Febvre 1932: Febvre, L. 1932. “Chiffres faux, courbes vraies?", Annales 4, 18, 585-586.  

Finley 1973: Finley, M. 1973. The Ancient Economy (University of California Press).

Foxhall and Forbes 1982: Foxhall, L. and H.A. Forbes 1982. “Σιτομερεια,” Chiron 12, 41-90. Frank 1933-1940: Frank, T. 1933-1940. An Economic Survey of Ancient Rome 5 vol. (Baltimore).

von Freyberg 1988: von Freyberg, H.-U.1988. Kapitalverkehr und Handel im römischenKaiserreich (27 v. Chr.-235 n. Chr.) (Freiburg).

Garnsey et al. 1984: Garnsey, P., T. Gallant, and D. Rathbone. 1984. “Thessaly and the Grain Supply of Rome during the Second Century B.C.,” JRS 74, 30-44.

Gitler and Ponting 2003: Gitler, H. and M. J. Ponting. 2003. The silver coinage of Septimius Severus and his family (193-211 ad). A study of the Chemical Composition of the Roman and Eastern Issues (Milan).

Gráda and Chevet 2002: Gráda, Cormac Ó. And J.-M. Chevet. 2002. “Famine and Market in Ancien Régime France,” JEH 62, 706-733.

Grainger 1999: Grainger, J. D. 1999. “Prices in Hellenistic Babylonia,” Journal of the Economic and Social History of the Orient 42.3, 303-325.

Habicht 1975: Habicht, C. 1975. “New Evidence on the Province of Asia,” JRS 65, 64-91.

Harl 1996: Harl, K. 1996. Coinage in Roman Economy, 300 B.C.-700 A.D  (Baltimore).

Harris 1993: Harris, W.V. (ed.) 1993. “The Inscribed Economy, Production and distribution in the Roman empire in the light of instrumentum  domesticum,” Journal of Roman Archaeology suppl. series 6.

He and McGarrity 2004: He, L. T. and J. P. McGarrity. “Data errors in small data sets can determine empirical findings,” in AEJ 32.2, 89-99.

Heichelheim 1938: Heichelheim, F. 1938. “Roman Syria” ESAR IV, 138-140.

Hendy 1985: Hendy, M. 1985. Studies in the Byzantine Monetary Economy c.300-1450 (London).

Herz 1988: Herz, P. 1988. Studien zum römischen Wirtschaftsgesetzgebung: die Lebensmittelversorgung, (Wiesbaden).

Hollander 2007: Hollander, D.B. 2007. Money in the Late Roman Republic (Boston).

Hopkins 1980: Hopkins, K. 1980. “Taxes and Trade in the Roman Empire (200 BC-AD 400),” JRS 70, 101-125.

Hopkins 2002: Hopkins, K. 2002. “Rome, Taxes, Rents and Trade” in Scheidel, W. and S. von Reden (eds.)  The Ancient Economy (New York), 190-230.

Howgego 1985: Howgego, C. J. 1985. Greek Imperial Countermarks. Studies in the Provincial Coinage of the Roman Empire (London).

Hultsch 1864: Hultsch, F. 1864: Metrologicorum Scriptorum Reliquiae, vol I (Leipzig).

Jasny 1944a: Jasny, N. 1944. The Wheats of Classical Antiquity (Baltimore).

Jasny 1944b: Jasny, N. 1944. Wheat Prices and Milling Costs in Classical Rome (Stanford).

Jasny 1947: Jasny, N. 1947. “The Breads of Ephesus and their Prices” Agricultural History 21.3, 190-192.

Johnson 1938: Johnson, A.C. 1938. “Roman Egypt” ESAR II, 322-324.

Johnson et al. 2003/1961:  Johnson, A.C., P.R. Coleman-Norton, and F. C. Bourne. Clyde Pharr (ed.) 1961/2003. Ancient Roman Statutes, A translation with introduction, commentary, glossary, and index ( Clark).

Johnston 2007: Johnston, A. 2007. Greek Imperial Denominations, ca 200-275. A Study of the Roman Provincial Bronze Coinages of Asia Minor (London).

Jones 1963: Jones, T.B. 1963. “A Numismatic Riddle: Greek Imperials: The So-Called Imperial Greeks,” Proceedings of the American Philosophical Society, 107.4, 308-347. 

Katsari 2011: Katsari, C. 2011. The Roman Monetary System. The Eastern Provinces from the First to the Third Century AD (Cambridge).

Kessler and Temin 2008: Kessler D. and P. Temin. 2008. “Money and Prices in the Early Roman Empire” in William V. Harris (ed.) The Monetary Systems of the Greeks and Romans (Oxford), 159.

King and Walker 1976: King, C.E. and D.R. Walker. 1976. “Ptolemaic and Augustan Silver: The evolution of the Tetradrachm of Roman Egypt,” in D.R. Walker (ed.) The Metrology of the Roman Silver Coinage I (Oxford), 139-159.

Koder 1991: Koder, J. (ed.) 1991. Das Eparchenbuch Leons des Weisen, M. Kaplan (trad.)(Wien).

Kroll 1993: Kroll, J. H. 1993. Results of the excavations conducted by the American School of Classic Studies at Athens, XXVI, The Greek Coins (Princeton).

Kroll 1996: Kroll, J. H. 1996. “Hemiobols to Assaria: the Bronze Coinage of Roman Aigion,” in NC 156, 49-78.

Laurence 2005: Laurence, R. 2005. “Land Transport in Roman Italy: cost, practice, and the economy” in H. Parkins and C. Smith (eds.) 2005. Trade, Traders and the Ancient City (London), 125-144.

Le Rider 1986: Le Rider, G. 1986. “Les Alexandres d’argent en Asie Mineure et dans l’Orient séleucide au 3^e siècle av. j. –C. (c. 275-c. 225). Remarques sur le système monétaire des Séleucides et des Ptolémées,” in Journal des Savants 3.37, 3-51.

Lo Cascio 1981: Lo Cascio, E. 1981. “State and Coinage in the Late Republic and the Early Empire,” Journal of Roman Studies 71, 71-86.

Lo Cascio 1999: Lo Cascio, E. 1999. “Population of Roman Italy in Town and Country” in in J. Bintliff and K. Sbonias, (eds.) Reconstructing Past Population Trends in Mediterranean Europe (3000 B.C.-A.D. 1800)

Lo Cascio and Malanima 2005: Lo Cascio, E. and P. Malanima. 2005. “ Cycles and Stability: Italian Population before the Demographic Transition (225 B.C. – A.D. 1900),” Rivista di Storia Economica 21.3, 197-232.

Magdalino 2002: Magdalino, P. 2002. “Medieval Constantinople: Built Environment and Urban Development,” in A. E. Laiou (ed.) The economic history of Byzantium, From the Seventh through the Fifteenth Century (Washington), 529-537.

Magie 1951: Magie, D. 1951. “A reform in the exaction of grain at Cibyra under Claudius” in P. R. Coleman-Norton (ed.) Studies in Roman Economic and Social History in Honor of Allan Chester (London), 152-154.

Manacorda 1978: Manacorda, D. 1978. “The Ager Cosanus and the Production of the Amphorae of Sestius: New Evidence and a Reassessment,” JRS 68, 121-131.

Marin and Virlouvet 2003: B. Marin and C. Virlouvet (eds.) Nourrir les cités de Méditerranée, Antiquité – Temps modernes (Paris).

Martin-Kilcher 2004: Martin-Kilcher, S. 2004. “Amphorae in the Roman West: Discussion and Research since 1989,” in Transport Amphorae and Trade in the Eastern Mediterranean, Acts of the International Colloquium at the Danish Institute at Athens, September 26-29, 2002

Masschaele 1993: Masschaele, J. 1993. “Transport Costs in Medieval England,” EHR 46.2, 266-279.

Mavrogordato 1918: Mavrogordato, J. 1918. “Chronology of the coins of Chios; Part V,” NC 4^th series, 18, 1-79.

Mayerson 1998: Mayerson, P. 1998. “The Sack (Cakkoc) is the Artaba Writ Large,” ZPE 122, 189-194.

Mayerson 2007: Mayeron, P. 2007. “The Case for 8.000.000 Modii in Justinian’s Edict 13.8,” BASP 44, 167-174.

McDonald 1989: MacDonald, D. 1989. “The Worth of the Assarion,” Zeitschrift für Alte Geschichte 38.1, 120-123.

Melville Jones 1971: Melville Jones, J.R. 1971. “Denarii, Asses and Assaria in the Early Roman Empire,” Bulletin of the Institute of Classical Studies of the University of London 18, 99-105.

Melville Jones 1993: Melville Jones, J.R. 1993. Testimonia Numaria.Greek and Latin Texts Concerning Ancient Greek Coinage (London).

Metcalf 1980#: Metcalf, W. 1980. The Cistophori of Hadrian. New York.

Miller 1972: Miller, S. G. 1972. “A Roman Monument in the Athenian Agora,” Hesperia 41, 50-95.

Mitchell 1976: Mitchell, S. 1976. “Requisitioned transport in the Roman Empire. A new inscription from Pisidia,” JRS 76, 106-131.

Montenegro 2001: Montenegro, A. 2001. “On sample size and precision in ordinary least squares,” JAS 28.5, 603-605.

Moritz 1958: Moritz, L.A. 1958. Grain-mills and flour in classical antiquity, (Oxford).

#Mrozek 1975: Mrozek, S. 1975. Prix et rémunération dans l’Occident romain (31 av. n.è.-250 de n.è.) ( Gdańsk).

Mundell Mango 2001: Mundell Mango, M. 2001. “Beyond the Amphora: non-Ceramic Evidence for Late Antique Industry and Trade” in S. Kingsley and M. Decker (eds.) Economy and Exchange in the East Mediterranean during Late Antiquity (Oxford), 95-102.

Oliver 1989 Oliver, J. H. 1989. “Greek Constitutions of Early Roman Emperors from Inscriptions and Papyri,” Memoirs of the American Philosophical Society 178, 237-238.

Picard 1998: Picard, O. 1998. “La valeur des monnaies grecques en bronze,” RN 6, 153, 7-18.

Pankiewicz 1994: Pankiewicz, R. 1994. “Les prix et l’argent dans le Nouveau Testament,” Pomerium 1, 87-100.

Pleket 1990: Pleket, H.W. 1990. “Wirtschafts-und Sozialstruktur” in F. Vittinghof (ed.) Europäische Wirtschafts- und Sozialgeschichte in der römischen Kaiserzeit (Stuttgart), 25-160.

Price 1987: Price, M. 1987.“Southern Greece“ in Burnett, A. M. and M. H. Crawford (eds.), The Coinage of the Roman World in the Late Republic. Proceedings of a colloquium held at the British Museum in September 1985 (Oxford), 95-103.

Puglisi 2011: Puglisi, M. 2011. “Coin circulation as a source for quantifying monetary supplies.” in de Callataÿ (ed.), Quantifying Monetary Supplies in Greco-Roman Times (Bari), 181-197.

Rathbone 1983a: Rathbone, D. 1983. “The Weight and Measure of Egyptian Grain,” ZPE 53, 265-275.

Rathbone 1983b: Rathbone, D. 1983. “The Grain Trade and Grain Shortages in the Hellenistic East” in P. Garnsey and C. R. Whittaker (eds.) Trade and Famine in Classical Antiquity, 45-55.

Rathbone 1987: Rathbone, D. 1987. “The Ancient Economy and Graeco-Roman Egypt” in L. Criscuolo and G. Geraci (eds.) Egitto e storia antica dall’ellenismo all’età araba: bilancio di un confronto, Atti del colloquio internazionale (Bologna), 159-176.

Rathbone 1996: Rathbone, D. 1996. “Monetisation, not price-inflation, in third-century A.D. Egypt?” in C.E. King and D.G. Wigg (eds.) 1996. Coin Finds and Coin Use in the Roman World: The Thirteenth Oxford Symposium on Coinage and Monetary History (Oxford), 321-339.

Rathbone 1997: Rathbone, D. 1997. “Prices and price formation in Roman Egypt” in J. Andreau, P. Briant, and R. Descat (eds.) Economie antique: prix et formation des prix dans les économies antiques, Entretiens d’archéologie et d’ histoire (Saint-Bertrand-de-Comminges), 183-244.

Rathbone 2003: Rathbone, D. 2003. “The Financing of Maritime Commerce in the Roman Empire, I-II AD,” in E. Lo Cascio (ed.) Credito e moneta nel mondo romano (Bari), 197-229.

Rathbone 2009: Rathbone, D. 2009. “Earnings and Costs: Living Standards and the Roman Economy” in A.K. Bowman and A. Wilson (eds.) Quantifying the Roman Economy: Methods and Problems (Oxford), 299-326.

Rathbone 2011: Rathbone, D. 2011. “Mediterranean grain prices c. 300 to 31 B. C.: the impact of Rome”, in Baker, H. and M. Jursa (eds.), Too Much Data? Generalization and Model-Buildings in Ancient Economy on the Basis of Large Corpora of Documentary Evidence. (Forthcoming, Oxford).

Robert and Robert 1954: Robert, L. and J. Robert 1954. La Carie. Histoire et Géographie historique avec le recueil des inscriptions antiques. T. II. Le plateau de Tabai et ses environs (Paris).    

Rea 1972: Rea, J.R. 1972. Oxyrhynchus Papyri XL ( London ).

Reger 1993a: Reger, G. 1993. “The Public Purchase of Grain in Independent Delos,” CA 12.2, 300-334.

Reger 1993b: Reger, G. 1993. Regionalism and Change in the Economy of Independent Delos (Oxford).

Reger 1997: Reger, G. 1997. “The Price Histories of Some Imported Goods on Independent Delos,” in J. Andreau, P. Briant and R. Descat (eds.) Economie antique, Prix et formation des prix dans les économies antiques, Entretiens d’archéologie et d’histoire (Saint-Bertrand-de-Comminges), 53-72.

Rickman 1980: Rickman, G. 1980. The Corn Supply of Ancient Rome (Oxford).

Robinson 1924: Robinson, D.M. 1924. “A New Latin Economic Edict from Pisidian Antioch,” TAPhA 55, 5-20.

Rogers 1866: Roger, J. E. T. 1866. History of Agriculture and Prices in England (Oxford).

Romer 1990: Romer, C. 1990. “The Great Crash and the Onset of the Great Depression,” QJE 105, 597-624.

Scheidel 2002: Scheidel W. 2002. “A model of demographic and economic change in Roman Egypt after the Antonine Plague,” JRA 15, 97-114.

Scheidel 2007: Scheidel, W. 2007. “A model of real income growth in Roman Italy,”  PSWPC February 2007. <www.princeton.edu/~pswpc/pdfs/scheidel/020701.pdf >

Scheidel 2009: Scheidel, W. 2009. “Real wages in Roman Egypt: A contribution to recent works on pre-modern living standards,” PSWPC  September 2009, Version 4.0 <http://www.princeton.edu/~pswpc/pdfs/scheidel/090904.pdf>

Sirks 1991: Sirks, B. 1991. Food for Rome: the Legal Structure of the Transportation and Processing of Supplies for the Imperial Distributions in Rome and Constantinople (Amsterdam).

Sosin 2002: Sosin, J. 2002. “Grain for Andros,” Hermes 130.2, 131-145.

Sperber 1965: Sperber, D. 1965. “Cost of Living in Roman Palestine I,” Journal of the Economic and Social History of the Orient 8.3, 248-271.

Sperber 1966: Sperber, D. 1966. “Cost of Living in Roman Palestine II,” Journal of the Economic and Social History of the Orient 9.3, 182-211.

Sperber 1991: Sperber, D. 1991. Roman Palestine 200-400, the Land - Crisis and change in Agrarian Society as reflected in Rabbinic sources, Ramat-Gan (1978) ( Bar-Ilan University Press).

Studenmund 2011: Stuenmund, A.H. 2011. Using Econometrics: A practical guide (Old Tappan).

Taus 2006: Taus, P.  2006 “Virtual reality in the Study of Archaeological sites: a data-base for Fanum Fortunae, The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 34.5, 330-334.

Tchernia 1995: Tchernia, A. 1995. “ Moussons et monnaies: les voies du commerce entre le monde gréco-romain et l'Inde” in Annales. Histoire, Sciences Sociales, 50.5, 991-1009.

Tchernia 2003: Tchernia, A. 2003. “ Le ravitaillement de Rome: les réponses aux contraintes de la géographie” in Nourrir les cites. 45-60.

Tchernia 2011: Tchernia A. 2011. Les Romains et le commerce (Naples).

Temin 2001: Temin, P. 2001. “A Market Economy in the Early Roman Empire,” Journal of Roman Studies 91, 169-181.

Temin 2006: Temin, P. 2006. “The Economy of the Early Roman Empire,” Journal of Economic Perspectives 20-1, 133-151.

Thurmond 2006: Thurmond, D.L. 2006. A Handbook of Food Processing in Classical Rome: For Her Bounty no Winter (Boston).

Varone 2000: Varone, “Spigolature epigrafiche ercolaneoi,” Rivista di Studi Pompeiani, 11, 2000, 276-281.

Wallace 1969: Wallace, S.L. 1969. Taxation in Egypt from August to Diocletian (New York).

Weir 1989: Weir, D.R. 1989. “Markets and Mortality in France, 1600-1789,” in Walter, J. and R. Schofield (eds.). Famine, Disease and the Social Order in Early Modern Society (Cambridge), 209-211.

Wörrle 1988: Wörrle, M. 1988. Stadt und Fest in kaiserlichen Kleinasien. Studien zu einer agonistischen Stiftung aus Oenoanda (Munich).