INTRODUCTION: DEFINITIONS AND FOUNDATIONS

The just price and usury were once inseparably linked by historians – indeed, for some people the two still constitute the sum total of medieval economic thought. In fact, they are completely different. The just price was accepted by the scholastics as grounded on justice and equality, either arithmetical or proportional, while usury – that is, making a charge for lending money – was grounded on injustice and inequality.

How was usury defined? Usury was concerned with lending, especially the lending of money, although it could be applied to anything that could be counted, weighed, or measured. The definitions were based ultimately on biblical texts, both Old Testament ones along the lines of ‘Take thou no usury …’ (Leviticus 25.36), and the New Testament Sermon on the Mount of Luke 6.35, ‘Lend, hoping for nothing again.’ Two definitions feature in Gratian's Decretum, both of them citing patristic texts. They emphasize two different aspects of the question. The first is ‘expecting to receive back more than you have given’ in a loan, whether of money or anything else, and it underlines the sinful intention of the usurer. It echoed the Luke text, and formed the basis for the all-important idea that the sinful hope was what defined usury. Urban III (1185–87) issued a decretal called Consuluit, where he quoted the Luke text, and made the point that usury was a sin of intention. This became the acid test.