Catechism of the Catholic Church §65 — excerpt
"In many and various ways God spoke of old to our fathers by the prophets, but in these last days he has spoken to us by a Son."
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. John of the Cross, the Ascent of Mount Carmel 2, 22, 3-5 in The Collected Works of St. John of the Cross, tr. K. Kavanaugh OCD · O. Rodriguez OCD (Washington DC: Institute of Carmelite Studies, 1979), 179-180: LH, Advent, week 2, Monday, OR