Spiritual writers often distinguish between four ends of prayer, that is, four reasons why one may go to prayer. They are usually articulated as: Adoration, Thanksgiving, Contrition (or Expiation), and Petition.
By Adoration, the one at prayer acknowledges that God is, in-and-of Himself, the Supreme and Perfect Being. He is lacking in nothing. It is natural for man to acknowledge those who excel in various fields. If this is the case with respect to other men, how much more should it be with God Who has no defects and is not lacking in any way. This Adoration is not based on the benefits which God has bestowed upon His creatures. It is rooted only in God’s own perfections. This is seen in the Gloria where the Church sings, “We praise Thee. We bless Thee. We adore Thee. We glorify Thee. We give Thee thanks,” not for anything You bestowed on creatures but solely “for Thy great glory.”
By Thanksgiving, the one at prayer expresses his thanks to God for all that He has bestowed upon him. For not only did God create him out of nothing, but God maintains him in existence from moment to moment. If God were to withdraw His conservative support, the man would fall back into the nothing from which he was created. Even more, every good which the one at prayer has, both natural and supernatural, has its origin in God. Because of all of the aforesaid, the creature has a debt of infinite gratitude towards the Creator, a debt which is acknowledged by acts of worship and thanksgiving. Such a debt, however, can never be fully discharged by purely creaturely acts.
Another debt arises between the one at prayer and God due to sin. Sin is an offense against God, which the sinner appeases by acts of penance (Expiation) which flow from internal sorrow (Contrition). In this type of prayer, one asks God to forgive him his sins. Any prayer can be used for this end, when offered up in a spirit of repentance and contrition, but there are certain prayers, such as Acts of Contrition and the Seven Penitential Psalms, which more clearly express this end.
Petition is when the one at prayer asks God for necessities and desires, both spiritual and material. By such a prayer, one acknowledges that God can provide all and expresses a trust that God will fulfill His promises.
It must be noted that there is a hierarchy among these four different ends of prayer. Adoration is the highest as it deals with God in Himself. Next comes Thanksgiving, for this acknowledges the proper relation between the creature and the Creator. Then comes Contrition, as this seeks to repair what has been injured in this relationship. Lastly, there is Petition, as it is the most focused on the creature. Normally, the time one spends praying according to each end should be proportional to the place it has in this hierarchy. For example, if one is spending all, or most, of one’s time at prayer asking God for things, and only little or no time on the other ends, then the order is being disregarded. Now there may be occasions, due to certain circumstances, such as being in great need or it being a time of penance set aside by the Church (such as Lent), where more focus will be given to one of these over the others. But, in general, this hierarchy is to be observed. So then, when one goes to prayer, one should always keep these ends and their proper order of them in mind. Every Christian, then, from time to time, should evaluate his prayer life to see if the proper order is being followed and, as the case may be, make any necessary corrections.