Chapter 1 — Preface to the Roman Catechism
Section 3. It is true that the invisible things of God from the creation of the world are, as the Apostle teaches, clearly seen, being understood by the things that are made: his eternal power also, and divinity. But the mystery which hath been hidden from ages and generations so far transcends the reach of man's understanding, that were it not made manifest by God to His Saints, to whom He willed to make known by the gift of faith, the riches of the glory of this mystery among the Gentiles, which is Christ, man could by no effort attain to such wisdom.