Catechism of the Catholic Church §1823 — excerpt
Jesus makes charity the new commandment. By loving his own "to the end," he makes manifest the Father's love which he receives. By loving one another, the disciples imitate the love of Jesus which they themselves receive.
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.