Catechism of the Catholic Church §1750 — excerpt
The morality of human acts depends on: - the object chosen; - the end in view or the intention; - the circumstances of the action.
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.