Catechism of the Catholic Church §1984 — excerpt
The Law of the Gospel fulfills and surpasses the Old Law and brings it to perfection: its promises, through the Beatitudes of the Kingdom of heaven; its commandments, by reforming the heart, the root of human acts.
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.