HKB
this they pray. But they pray for us who lack the ultimate perfection of bliss: and their prayers are efficacious in impetrating through their previous merits and through God's acceptance.
Reply Obj. 2: The saints impetrate what ever God wishes to take place through their prayers: and they pray for that which they deem will be granted through their prayers according to God's will.
Reply Obj. 3: Those who are in Purgatory though they are above us on account of their impeccability, yet they are below us as to the pains which they suffer: and in this respect they are not in a condition to pray, but rather in a condition that requires us to pray for them.
Reply Obj. 4: It is God's will that inferior beings should be helped by all those that are above them, wherefore we ought to pray not only to the higher but also to the lower saints; else we should have to implore the mercy of God alone. Nevertheless it happens sometime that prayers addressed to a saint of lower degree are more efficacious, either because he is implored with greater devotion, or because God wishes to make known his sanctity.
Reply Obj. 5: It is because the saints while living merited to pray for us, that we invoke them under the names by which they were known in this life, and by which they are better known to us: and also in order to indicate our belief in the resurrection, according to the saying of Ex. 3:6, "I am the God of Abraham," etc.
TWELFTH ARTICLE [II-II, Q. 83, Art. 12]
Whether Prayer Should Be Vocal?
Objection 1: It would seem that prayer ought not to be vocal. As stated above (A. 4), prayer is addressed chiefly to God. Now God knows the language of the heart. Therefore it is useless to employ vocal prayer.
Obj. 2: Further, prayer should lift man's mind to God, as stated above (A. 1, ad 2). But words, like other sensible objects, prevent man from ascending to God by contemplation. Therefore we should not use words in our prayers.
Obj. 3: Further, prayer should be offered to God in secret, according to Matt. 6:6, "But thou, when thou shalt pray, enter into thy chamber, and having shut the door, pray to thy Father in secret." But prayer loses its secrecy by being expressed vocally. Therefore prayer should not be vocal.
On the contrary, It is written (Ps. 141:2): "I cried to the Lord with my voice, with my voice I made supplication to the Lord."
I answer that, Prayer is twofold, common and individual. Common prayer is that which is offered to God by the ministers of the Church representing the body of the faithful: wherefore such like prayer should come to the knowledge of the whole people for whom it is offered: and this would not be possible unless it were vocal prayer. Therefore it is reasonably ordained that the ministers of the Church should say these prayers even in a loud voice, so that they may come to the knowledge of all.