Usury is really necessary and of benefit to no group of persons; and if all lived virtuously there would be no need of it. Not only is usury unnecessary, but it is a positive and terrible evil. It has a disastrous effect on the city and on the social organism. The public usurers are usually foreigners, and they drain the wealth of the city into other lands. Again, usury concentrates the money of the community in the hands of few, just as if all the blood in a man’s body ran to his heart and left his other organs depleted.

From Noonan, The Scholastic Analysis of Usury (Harvard, 1957), but don’t ask me what work of St B’s it’s from because I didn’t photocopy the bibliography. Bad me.