Among those who are guilty of robbery are also included persons who do not pay, or who turn to other uses or appropriate to themselves, customs, taxes, tithes and such revenues, which are owed to the Church or civil authorities.
To this class also belong usurers, the most cruel and relentless of extortioners, who by their exorbitant rates of interest, plunder and destroy the poor. Whatever is received above the capital and principal, be it money, or anything else that may be purchased or estimated by money, is usury; for it is written in Ezechiel: He hath not lent upon usury, nor taken an increase; and in Luke our Lord says: Lend, hoping for nothing thereby. Even among the pagans usury was always considered a most grievous and odious crime. Hence the question, “What is usury ?” was answered: “What is murder?” And, indeed, he who lends at usury sells the same thing twice, or sells that which has no real existence.