Chapter 6.
60 You find, then, that the Father created and the Spirit created; learn, too, that the Son of God also created, when Solomon says: “Wisdom has made herself a house.” How, then, can the Holy Spirit Who created the mystery of the Lord's Incarnation, which is above all created things, be Himself a creature?
61. As we have shown above generally that the Holy Spirit is our Creator according to the flesh in the outer man, let us now show that He is our Creator also according to the mystery of grace. And as the Father creates, so too does the Son create, and so too the Holy Spirit creates, as we read in the words of Paul: “For it is the gift of God, not of works, lest any one should boast. For we are His workmanship created in Christ Jesus in good works.”
Source: On the Holy Spirit (New Advent)