‘The market makes its money’, thought Hicks, and similar messages have been delivered by many other thinkers on money. However, while students of money have mostly been concerned with who could or should produce it, the market or the state, few have questioned whether the money itself should be single or not. Apparently it has been taken for granted that a single market and a single money should coincide. Nevertheless, contrary to the modern assumption that one single currency should operate in one country, the history of money has been full of plurality until recent times, as we will argue in this issue. It is no exaggeration to say that the majority of human beings through most of history dealt with concurrent currencies. It is important to recognise that, in most if not in all cases, the coexistence of monies was not incidental but functional, since they worked in a complementary relationship. That is, one money could do what another money could not, and vice versa. In other words, an assortment of monies could do what any single money could not, and supply what the market required. In the following articles we will show how this worked.

The coexistence of a number of monies with fluctuating exchange rates in modern China and other Asian regions appeared chaotic to foreign observers. However, behind this apparently confused situation lay a multiplicity of currency circuits, each of which consisted of pairing a trade zone with a particular currency. Their concurrence resulted from the difference of temporality and space in monetary usage. The difficulty of matching heterogeneous demands for money to uneven supplies of currencies made for multiple currency circulation. Such a multiplicity caused some merchants to make use of imaginary units which were alive only in account books. Though complementary relationships between incompatible monies prevailed in China, India and other regions, a combination of a remittance system and local credit supply in some societies happened to synchronise currency streams to make a compatible monetary system. This comparative study suggests that currency streams often had to pass through multiple market layers, and that some friction in the streams meant that the market required plural monies.

In its Asian operations the Dutch United East Indies Company (VOC) (1602–1798) acted both as a territorial ruler and as a trading company. The company shipped large amounts of precious metals to Asia, both in the form of bullion and as coins, to pay for its trade and to provide currency for the areas under its control. The Company faced the problem that silver coins rapidly disappeared from circulation, as demand for silver was high in Asia. The Company attempted to manage the problem with a monetary policy using a unit of account, modelled after the policy of the Dutch Republic. It turned out that the two purposes of the money of account system, viz., putting the bookkeeping on a systematic basis and managing the currency in circulation, were conflicting. The first demanded a fixed unit of account, the second demanded a flexible policy of linking and de-linking the unit of account to real coins. Although the Company managed to muddle through this dilemma, it only succeeded in finding temporary solutions.

The monetary system of late medieval and early modern Europe has been commonly described as irrational, in the light of later commodity money standards. In particular, the alterations in the legal value and/or in the metal content of most coins throughout this period have been regarded as a source of disorder and as a product of ignorance and abuse. This article suggests that the whole system, and its apparently awkward articulations, may have been deliberately designed to ensure complementarity between domestic and foreign trade. From this perspective, monetary alterations appear as the levers of a peculiar form of monetary policy, with an extra degree of freedom compared to more modern instruments, and equally open to being managed or mismanaged.

Complementarity of money means that two or more kinds of monies together fulfil the demands of the users better than they would without the existence of the other(s). In this article we study complementarity between paper monies in Sweden. We address four questions: 1. What was used as money at a macro-level (money supply) and at a micro-level (monetary remittances)? 2. What was the relative value of different monies in parallel circulation? 3. Were there seasonal variations in use and/or value of these monies? 4. Were there geographical variations in use and value? What we find is that the complementarity helped to solve the problem of providing sufficient liquidity domestically over time and space and thus contributed to the maintenance of a stable value of the currency.