“Et incidunt primo in damnum spirituale. Unde dicit erraverunt a fide. Cuius ratio est, quia per sanam doctrinam fidei prohibentur multa illicita lucra, a quibus desistere nolunt, et inveniunt sibi aliam doctrinam, ubi eis sit spes salutis. Et hoc specialiter faciunt usurarii.”

– S. Thomas de Aquino, Super I Tim., cap. 6 l. 2

“They fall first of all into spiritual harm; hence he says, they have erred from the faith. The reason for this is that sound doctrine forbids many unlawful profits which they refuse to give up; consequently, they invent their own doctrine which creates for them a new hope of salvation. This is what usurers often do.”

– St Thomas Aquinas, Commentary on the Letters of St Paul to the Philippians, Colossians, Thessalonians, Timothy, Titus, and Philemon (Aquinas Institute: Lander, 2012), 331.