“Usury changes things. with interest rates, money is no longer a simple and stable commodity that just happens to have been chosen as a medium of exchange. Projected through time, it multiplies, and this without any toil on the part of the usurer. Everything becomes more fluid. A man can borrow money, buy a loom, sell his wool at a high price, change his station in life. Another man can borrow money, buy the first man’s wool, ship it abroad, and sell it at an even higher price. He moves up the social scale. Or if he is unlucky, or foolish, he is ruined. Meanwhile, the usurer, the banker, grows richer and richer. We can’t even know how rich, because money can be moved and hidden, and gains on financial transactions are hard to trace. It’s pointless to count his sheep and cattle or to measure how much land he owns. Who will make him pay his tithe? Who will make him pay his taxes? Who will persuade him to pay some attention to his soul when life has become so interesting? Things are getting out of hand.”
Tim Parks in Medici Money: Banking, Metaphysics, and Art in Fifteenth-Century Florence
Have you ever considered a time before interest was charged?