Chapter IV: On Internal Sins

St. Alphonsus, V, 12; ed. G., II, p. 720; H. Ap., III, 47; Vind. Alph., P. 2, q. 2; Aertnys, I, n. 236; Lehmkuhl, I, n. 353; Ami du Cl., 1912, p. 1025.

345. Internal sins, as such, are all evil acts elicited by the will and deliberately willed, which are perfected in the mind. Concerning these the Tridentine Synod warns (Sess. XIV, c. 5) "that sometimes they wound the soul more gravely, and are more dangerous than those which are admitted openly." The reason is because they are more easily perpetrated, are less cared for, and especially in the article of death expose the soul to the danger of damnation (Inst. cat., P. I, c. 6, n. 4).

Internal sins are reduced to a threefold class: 1. to desire and purpose, which regard future time; 2. to joy or complacency, which look to past time; 3. to delectation, which refers itself to present time.