Catechism of the Catholic Church §311 — excerpt
Angels and men, as intelligent and free creatures, have to journey toward their ultimate destinies by their free choice and preferential love. They can therefore go astray.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: St. Augustine, De libero arbitrio I, 1, 2: PL 32, 1221- 1223 · St. Thomas Aquinas, STh I-II, 79, 1 · St. Augustine, Enchiridion II, 3: PL 40, 236