Catechism of the Catholic Church §244 — excerpt
The eternal origin of the Holy Spirit is revealed in his mission in time. the Spirit is sent to the apostles and to the Church both by the Father in the name of the Son, and by the Son in person, once he had returned to the Father.
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.