Contracts lie at the very core of economic thought. A simple purchase is a type of contract, the use of money another. Property rights are also grounded in the idea of a contract, at least since the early modern period. Aristotle had argued in favor of private property, primarily with appeals to security and superior stewardship. Aquinas reinforced these claims but also argued that in the case of a famine or siege, one might appropriate available foods to fulfil the Christian dictate of self-pre