On the contrary, It is written (2 Macc. 15:14): "This is . . . he that prayeth much for the people, and for all the holy city, Jeremias the prophet of God."
I answer that, As Jerome says (Cont. Vigilant. 6), the error of Vigilantius consisted in saying that "while we live, we can pray one for another; but that after we are dead, none of our prayers for others can be heard, seeing that not even the martyrs' prayers are granted when they pray for their blood to be avenged." But this is absolutely false, because, since prayers offered for others proceed from charity, as stated above (AA. 7, 8), the greater the charity of the saints in heaven, the more they pray for wayfarers, since the latter can be helped by prayers: and the more closely they are united to God, the more are their prayers efficacious: for the Divine order is such that lower beings receive an overflow of the excellence of the higher, even as the air receives the brightness of the sun. Wherefore it is said of Christ (Heb. 7:25): "Going to God by His own power . . . to make intercession for us" [*Vulg.: 'He is able to save for ever them that come to God by Him, always living to make intercession for us.']. Hence Jerome says (Cont. Vigilant. 6): "If the apostles and martyrs while yet in the body and having to be solicitous for themselves, can pray for others, how much more now that they have the crown of victory and triumph."
Reply Obj. 1: The saints in heaven, since they are blessed, have no lack of bliss, save that of the body's glory, and for 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.