Modern economics is almost entirely silent on the issue of usury, recognizing it mostly as a curious form of price control that has since passed into history. Opposition to usury remains central to modern Islamic banking institutions, which are based on the Quran's prohibition of usury. Furthermore, there are still legislative efforts to control the rate of interest on everything from consumer credit cards to payday lenders to student loans. Modern economic analysis suggests that even well-intentioned efforts to protect the poor from 'excessive' rates of interest are ill advised. The lessons to be learned from studying the intellectual evolution of lending with interest apply well beyond the issue of usury. In fact, scholarly attitudes toward financial markets, lending, and interest reflect more general attitudes toward commerce itself. They also reflect how well-intentioned policy might in fact carry unintended consequences that harm the very people the policy intends to help.