Money, trust, transactions-these three keywords that seem to describe our (post) modern age, have been the motor of most societies ever since. Coins embody abstract concepts of value, measure, legal tender, and exchange; and these concepts, by framing the production, use, and receptions of the coins, shape and even reshape the coins' materiality and thus their affordances. This holds especially true for ancient times. Flans of bronze, silver, and gold were minted into coins by workers, using engraved dies that "coined" images and legends into the surface and thus made them valid currency. Yet, there occurred, at times, overstrikes, countermarks, scratches, erasures, graffiti, drills-and the metal coins preserve and store all such alterations until now, what makes them readable like a "biography". This unfolds narrations of ever-changing affordances and thus stimulates modern research with questions about the interdependencies of institutions, human interactions, and the material qualities of things that have impact on human life. Not surprisingly, the primary affordance of coins is to serve as money. Acceptance and trust are two basic conditions to guarantee money's smooth circulation and thus enable economic transactions and exchange. Ruptures in this system challenge the affordances of coins, but also create new affordances, as we will show in three case studies from the Roman imperial period. In all these cases, coin denominations and regional limits of coin circulation are key factors for challenging and recreating affordances. This brings us back to the overall ruling monetary function of coins, being the backbone and mirror of financial, political, and socioeconomic systems. Nonetheless, reflecting and discussing the material and visual aspects of coins and their impact on us makes us think afresh about our relationship with the world, all the more in our modern, increasingly virtualized society.

How, in historical societies, did people finalise transactions? Over the past few decades many economic and social historians have concerned themselves with this question, following the examples set by Douglass North and Craig Muldrew. Surprisingly, they have almost completely disregarded the most straightforward solution that historical societies had to offer, namely by using coins and currencies. Those scholars assumed, in part, that credit instruments were much more important in day-to-day trade. In this introduction we argue that studies into the unequal socioeconomic distribution of media of ex-change – coins, currencies, and credit instruments – reveal mechanisms that are crucial to understanding broader social and economic processes. To this end, we discuss how the five articles in this special issue contribute to the growing literature on this topic.

There have been important advances by archeologists and numismatists in recent decades in the study of the beginnings of coinage in Ionia, Lydia, and Greece before the fifth century B.C. This paper provides a model of the birth of coinage that brings these advances into a broad analysis of the subject-matter. It pulls together many factors that are often treated separately. In addition, the model yields one important new result. Contrary to popular assumption, early coinage was not highly profitable. The Lydian government and the Greek city-states provided an extremely wide array of denominations of coins in a single precious metal at considerable cost. Their willingness to bear this cost must have reflected a political strategy of promoting coinage. Such a political strategy would also be easy to explain. As a large payer and recipient of money in the form of precious metals, the government had much to gain from the spread of coinage in order to economize on transaction costs in its own affairs. . Introduction The origins of coinage around  B.C. in Ionia or Lydia never cease to arouse curiosity. A fundamental puzzle is that the coinage consisted of electrum, an uncertain mixture of gold and silver. Yet outside archeology and related sub-disciplines, it is still largely unnoticed that recent advances in the study of early coinage basically resolve the mystery. This makes it a fitting time to propose a general model of the birth of coinage. A model has a number of advantages. Discussions of early coinage often put the emphasis on one aspect or another, such as the ability of government to coerce, or market incentives. A model can do better: it permits fitting all the pieces together without privileging one aspect relative to the rest. In addition, by requiring explicit reasoning, a model can open up new vistas. In the present case, the model casts doubt on one important assumption in the literature: namely, that early coinage was highly profitable. This assumption sits badly with some of the facts, especially the decision of the Lydian government to provide an extremely wide array of denominations of coins in a single precious metal. The Greek city-states that followed in the Lydian footsteps about  years later (using silver instead of electrum) did the same. The difficulty is clear: we know from broad historical evidence from other times and places that providing a wide range of denominations in a single metal could only have been possible with the relevant technology at a considerable cost. Indeed, examples of similar government behavior are hard to find before the eighteenth century, if not the nineteenth. Most likely, this behavior of the governments of Lydia and Greece was part of a political strategy of promoting coinage during its infancy. Such a political strategy would also be easy to explain. As a large payer and recipient of money in the form of precious metals, the government had much to gain from the spread of the habit of using coins instead of bullion