During the Middle Ages only the Jews were permitted to take interest. St. Thomas Aquinas agreed with Aristotle that taking of interest was usury and the Church acted accordingly. The lender, however, was permitted to take compensation for the gain he would forego, the loss he would encounter, the risk he would run, or whatever other external title their might be. But the Reformers, who either thought that they had to liberate a suffering humanity from the shackles of a terrorizing Church or believed that they had to give some compensations in return for their own brutal regimentation, permitted the charging of interest; thus the formation of modern capitalism was promoted.
Francis Stuart Campbell, The Menace of the Herd