In the preface to his exploration of trust in Greece of the classical period, Steven Johnstone declares his hope that his book will be read as a provocation (p. x). He is not likely to be disappointed. In a volume of modest size, Johnstone presents new interpretations of many canonical texts for the economic history of Athens and the other city-states of Greek antiquity, all the while sidestepping the concerns of the New Institutional Economics (NIE), thus modeling an alternative to the dominant theoretical orientation of his field. For a much more explicit critique of NIE in ancient history, see Francesco Boldizonni's The Poverty of Clio: Resurrecting Economic History (Princeton, NJ: Princeton University Press, 2011). For Johnstone, the goal is rather to show how much these texts have to tell us beyond a lesson about the performance-enhancing effects of transaction-cost-lowering institutions. Or, where some have emphasized the reduction of transaction cost, as in Josiah Ober's treatment of Nikophon's law on silver coinage (Democracy and Knowledge: Innovation and Learning in Classical Athens. Princeton, NJ: Princeton University Press, 2008: 220–45), Johnstone notes the redistribution of transaction cost between buyers and sellers. Informed by the work of sociologists Niklas Luhmann and Anthony Giddens, the overarching interest of the book is in the dynamic interplay of personal relationships of trust (or distrust) and abstract systems of trust, in economics, politics, and in between. Yet because the focus is steadfastly trained on practices, e.g., not money or the monetary system per se, but on how people actually used money, this reads like a sensitive anthropologist's account of a distant culture. The drive to defamiliarize the ancients is balanced by a desire to know how things really worked. How would Socrates have calculated his net worth?

This is not a restatement of the primitivist position in the age-old debate on the ancient economy. In the roughly half of the book devoted to economic phenomena, Johnstone illuminates techniques of measuring, accounting, and valuing that are sophisticated and exact. He asks not whether Socrates was capable of accurately calculating the value of his estate. Nor is economic rationality the issue: Socrates as homo oeconomicus is not put on trial. The question is what, for the Greeks, would have constituted “accurate?” Without a central land registry, and given the qualitatively uneven nature of the land, it is argued that no functioning market in land existed and thus no abstract capital value. Instead, in the absence of conflict, either over inheritance, fiscal liability, or political power, the Greeks trusted each other to unilaterally value their properties by whatever means they saw fit. Usually, Socrates’ guesstimate of 5 minai was just fine. When conflict arose, trust evaporated or was reinvested in experts, who made an ad hoc valuation by focusing on what they could easily enough see: the perimeter of a plot, the annual income accruing to the estate, and debts. The cognitive and technical resources put on display are sophisticated, but Johnstone's emphasis is on the specific social context and limited scope of their deployment.

His treatment of measuring grain comes to similar conclusions. The Greeks were certainly capable of measuring grain precisely. It was just costly, 2 percent of the eventual sale price in one notable case. The Greeks were also capable of abstracting certain amounts of grain into fungible units of standard, though notional, volume: medimnoi. On the ground, these were Johnstone's “heaps,” variegated in density, and thus in weight, as well as in their quality grade. Again, the argument is that the more sophisticated form of measuring was deployed selectively, restricted to two situations of generalized distrust. The first is unsurprisingly under the cloud of corruption. Greek cities regularly entrusted commissioners with buying or securing at an acceptable price part of the grain supply. Measuring by medimnoi helped protect the public from officials who wanted to profit from the spread between an administratively fixed price and a market price. The second situation is less obviously riven with distrust: retail trade in the agora, the city's carefully delimited commercial space, in which public officials enforced the use of standard weights and measures, and with less success than we have supposed, argues Johnstone, attempted to guarantee quality control. The rest of the time, the Greeks trusted each other to “eyeball” it, to assess value on the spot. Johnstone finds practical units of convenience where others have sought abstract measures. Thus the lion's share of the wholesale grain trade was based on the phormos, the amount of grain that could fit into a sealed sack, carried by a single man. Inside the household, wealth was tracked and in fact counted in containers of customary, but varying, size and shape. Fascinating use is made of Reviel Netz’ work on Greek counting (“Counter Culture: Toward a History of Greek Numeracy.” Journal of the History of Science 40 [2002]: 321–52). Only external pressure, or the peculiar demands of slavery, forced the family to take up abstract measures.

This book will fuel several local controversies in ancient economic history. Much of the debate on the scale of grain imports in classical Athens depends on different assessments of the harvest of 329/8 B.C.E. The upshot of Johnstone's take on priestly accounting tricks is that grain was less scarce that year than meets the eye (p. 51). He takes a skeptical view of the cliometric trend's conclusions from the few price series we possess (p. 47). Yet perhaps the most controversial element of the book will be its general view of an agora pervaded by asymmetrical transaction costs. In haggling, sellers have the advantage, and thus communities identify with buyers. These are bold claims given the vaunted Greek ideology of autarky. Since coinage produces this asymmetry, it is surprising that base metal, i.e., fiduciary coinage never enters into the analysis. Finally, a contrast is repeatedly drawn between the classical and the Hellenistic periods, which is only rarely unconvincing, as when Johnstone writes that “tariffs,” by which he seems to mean specific tariffs, differentiate the postclassical Greek city, citing only one imperfectly understood and unprovenanced inscription (p. 99). For those interested in the economic history of ancient Greece, this will prove to be one of the most important books written in years. And as a lagniappe, it is highly entertaining.