Roman Catechism 5.14

Chapter 5 — Part I: The Creed — Article III: Who Was Conceived by the Holy Ghost, Born of the Virgin Mary

Section 14. How To Profit By The Mystery Of The Incarnation — These truths comprise the substance of what appears to demand explanation regarding the admirable mystery of the Conception. To reap from them abundant fruit for salvation the faithful should particularly recall, and frequently reflect, that it is God who assumed human flesh; that the manner in which He became man exceeds our comprehension, not to say our powers of expression; and finally, that He vouchsafed to become man in order that we men might be born again as children of God. When to these subjects they shall have given mature consideration, let them, in the humility of faith, believe and adore all the mysteries contained in this Article, and not indulge a curious inquisitiveness by investigating and scrutinising them -- an attempt scarcely ever unattended with danger.