Roman Catechism 42.16

Chapter 42 — Part IV: Prayer — Amen

Section 16. First Explanation — The word amen, with which the Lord's Prayer concludes, contains, as it were, the germs of many of these thoughts and reflections which we nave just considered. Indeed, so frequent was this Hebrew word in the mouth of the Saviour, that it pleased the Holy Ghost to have it retained in the Church of God. Its meaning may be said to be: Know that thy prayers are heard. It has the force of a response, as if God answers the suppliant, and graciously dismisses him, after having favourably heard his prayers.