Chapter 33 — Part IV: Prayer — On Prayer in General
Section 26. The Two Chief Parts Of Prayer Petition And Thanksgiving — There are two principal parts of prayer, petition and thanksgiving, and since these are the sources, as it were, from which all the others spring, they appear to us to be of too much importance to be omitted. For we approach God and offer Him the tribute of our worship, either to obtain some favour, or to return Him thanks for those with which His bounty every day enriches and adorns us. God Himself indicated both these most necessary parts of prayer when He declared by the mouth of David: Call upon me in the day of trouble: I will deliver thee, and thou shalt glorify me.