useless to pray
and to worship God at all: of these it is written (Malach. 3:14):
"You have said: He laboreth in vain that serveth God." Another
opinion held that all things, even in human affairs, happen of
necessity, whether by reason of the unchangeableness of Divine
providence, or through the compelling influence of the stars, or on
account of the connection of causes: and this opinion also excluded
the utility of prayer. There was a third opinion of those who held
that human affairs are indeed ruled by Divine providence, and that
they do not happen of necessity; yet they deemed the disposition of
Divine providence to be changeable, and that it is changed by prayers
and other things pertaining to the worship of God. All these opinions
were disproved in the First Part (Q. 19, AA. 7, 8; Q. 22, AA. 2, 4;
Q. 115, A. 6; Q. 116). Wherefore it behooves us so to account for the
utility of prayer as neither to impose necessity on human affairs
subject to Divine providence, nor to imply changeableness on the part
of the Divine disposition.

In order to throw light on this question we must consider that Divine
providence disposes not only what effects shall take place, but also
from what causes and in what order these effects shall proceed. Now
among other causes human acts are the causes of certain effects.
Wherefore it must be that men do certain actions, not that thereby
they may change the Divine disposition, but that by those actions
they may achieve certain effects according to the order of the Divine
disposition: and the same is to be said of natural causes. And so is
it with regard to prayer. For we pray not that we may change the
Divine disposition, but that we may impetrate that which God has
disposed to be fulfilled by our prayers, in other words "that by
asking, men may deserve to receive what Almighty God from eternity
has disposed to give," as Gregory says (Dial. i, 8).

Reply Obj. 1: We need to pray to God, not in order to make known to
Him our needs or desires but that we ourselves may be reminded of the
necessity of having recourse to God's help in these matters.

Reply Obj. 2: As stated above, our motive in praying is, not that we
may change the Divine disposition, but that, by our prayers, we may
obtain what God has appointed.

Reply Obj. 3: God bestows many things on us out of His liberality,
even without our asking for them: but that He wishes to bestow
certain things on us at our asking, is for the s