Catechism of the Catholic Church §733 — excerpt
"God is Love" and love is his first gift, containing all others. "God's love has been poured into our hearts through the Holy Spirit who has been given to us."
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.