Chapter 32 — Part III: The Decalogue — The Ninth and Tenth Commandments
Section 14. If then it is sometimes lawful to covet, it must be conceded that not every species of concupiscence is forbidden. St. Paul, it is true, says that concupiscence is sin; but his words are to be understood in the same sense as those of Moses, whom he cites, as the Apostle himself declares when, in his Epistle to the Galatians he calls it the concupiscence of the flesh for he says: Walk in the -spirit, and you shall not fulfil the lusts of the flesh.