A Topic of Moral Theology
Intrinsically evil, and evil because forbidden
Acts bad in themselves against the natural law, and acts bad only because prohibited by lawful authority.
Also asked about as…
always wrong no matter what · intrinsically evil acts (ed.)
In the index as Act · Good · Moral subjectivism · Positivism
In the manuals
Read the manuals side by side → — each work's whole treatment in its own column
A Manual of Moral Theology for English-Speaking Countries
Vol. I, Bk. I, Ch. IV, Section I. The Essence of Morality, n. 4 — An action which in itself is not conformable to right reason and order is against the law of nature and intrinsically bad. An action which in itself is not bad, but only bad because forbidden for good reasons by a lawful… Read in context →
Summa Theologiae Moralis
Vol. I, General Moral Theology, Treatise: On Human Acts in…, Second Part: On Human Acts…, Section A: On the Morality…, Q. II, Article I: On the Intrinsic Difference Between Good and Evil, nn. ¶1, 121, 122 & 123 (24 passages — hover a number to read it)
Treated under the broader heading The Essence of Morality — Wouters, Manual of Moral Theology · McHugh–Callan, Moral Theology · Bucceroni, Commentaries on Human Acts · Gury-Ballerini, Compendium of Moral Theology (8th ed., 1884) · Vermeersch, Theologia Moralis · Prümmer, Manuale Theologiae Moralis · Konings, Theologia Moralis · Sabetti-Barrett, Compendium of Moral Theology · Billuart, Summa Summae — these works do not divide the matter as finely as we do here, so their treatment stands one heading up (ed.)