Reply Obj. 1: The will moves the other powers of the soul to its end, as stated above (Q. 82, A. 1, ad 1), and therefore religion, which is in the will, directs the acts of the other powers to the reverence of God. Now among the other powers of the soul the intellect is the highest, and the nearest to the will; and consequently after devotion which belongs to the will, prayer which belongs to the intellective part is the chief of the acts of religion, since by it religion directs man's intellect to God.
Reply Obj. 2: It is a matter of precept not only that we should ask for what we desire, but also that we should desire aright. But to desire comes under a precept of charity, whereas to ask comes under a precept of religion, which precept is expressed in Matt. 7:7, where it is said: "Ask and ye shall receive" [*Vulg.: 'Ask and it shall be given you.'].
Reply Obj. 3: By praying man surrenders his mind to God, since he subjects it to Him with reverence and, so to speak, presents it to Him, as appears from the words of Dionysius quoted above (A. 1, Obj. 2). Wherefore just as the human mind excels exterior things, whether bodily members, or those external things that are employed for God's service, so too, prayer surpasses other acts of religion. _______________________
FOURTH ARTICLE [II-II, Q. 83, Art. 4]
Whether We Ought to Pray to God Alone?
Objection 1: It would seem that we ought to pray to God alone. Prayer is an act of religion, as stated above (A. 3). But God alone is to be worshiped by religion. Therefore we should pray to God alone.
Obj. 2: Further, it is useless to pray to one who is ignorant of the prayer. But it belongs to God alone to know one's prayer, both because frequently prayer is uttered by an interior act which God alone knows, rather than by words, according to the saying of the Apostle (1 Cor. 14:15), "I will pray with the spirit, I will pray also with the understanding": and again because, as Augustine says (De Cura pro mortuis xiii) the "dead, even the saints, know not what the living, even their own children, are doing." Therefore we ought to pray to God alone.
Obj. 3: Further, if we pray to any of the saints, this is only because they are united to God. Now some yet living in this world, or even some who are in Purgatory, are closely united to God by grace, and yet we do not pray to them. Therefore neither should we pray to the saints who are in Paradise.
On the contrary, It is written (Job 5:1), "Call . . . if there be any that will answer thee, and turn to some of the saints."
I answer that, Prayer is offered to a person in two ways: first, as to be fulfilled by him, secondly, as to be obtained through him. In the first way we offer prayer to God alone, since all our prayers ought to be directed to the acquisition of grace and glory, which God alone gives, according to Ps. 83:12, "The Lord will give grace and glory." But in the second way we pray to the saints, whether angels or men, not that God may through them know our petitions, but that our prayers may be effective through their prayers and merits. Hence it is written (Apoc. 8:4) that "the smoke of the incense," namely "the prayers of the saints ascended up before God." This is also clear from the very style employed by the Church in praying: since we beseech the Blessed Trinity "to have mercy on us," while we ask any of the saints "to pray for us."