Chapter 1 — Preface to the Roman Catechism
Section 2. The Necessity Of Religious Instruction — Such is the nature of the human mind and intellect that, although by means of diligent and laborious inquiry it has of itself investigated and discovered many other things pertaining to a knowledge of divine truths; yet guided by its natural lights it never could have known or perceived most of those things by which is attained eternal salvation, the principal end of man's creation and formation to the image and likeness of God.