Catechism of the Catholic Church §2560 — excerpt
"If you knew the gift of God!" The wonder of prayer is revealed beside the well where we come seeking water: there, Christ comes to meet every human being.
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. Augustine De diversis quaestionibus octoginta tribus 64, 4: PL 40, 56