 Later Scholastics would devote considerable attention to developing and refining the notion of the just price. Of special concern was the price attached to the lending of money, or interest. Since the founding of the Catholic church, it was widely regarded as sinful for lenders to charge interest on their loans, and so-called “usury” was prohibited by canon and often by secular law. Much of the concern regarding usury seems to have been driven by the idea that the charging of interest involves an inequitable exchange—lenders give something to borrowers, but demand back more than they have given. But Aquinas seems to have been particularly concerned that borrowers would often be driven to take out loans out of necessity, and thus that their consent to the exchange is not fully voluntary (Summa Theologiae, part 2, second part, question 78).