II. INTERCESSION AND INVOCATION
We shall here speak not only of intercession, but also of the invocation of the saints. The one indeed implies the other; we should not call upon the saints for aid unless they could help us. The foundation of both lies in the doctrine of the communion of saints. In the article on this subject it has been shown that the faithful in heaven, on earth, and in purgatory are one mystical body, with Christ for their head. All that is of interest to one part is of interest to the rest, and each helps the rest: we on earth by honouring and invoking the saints and praying for the souls in purgatory, and the saints in heaven by interceding for us. The Catholic doctrine of intercession and invocation is set forth by the Council of Trent, which teaches that the saints who reign together with Christ offer up their own prayers to God for men. It is good and useful suppliantly to invoke them, and to have recourse to their prayers, aid, and help for obtaining benefits from God, through His Son Jesus Christ our Lord, Who alone is our Redeemer and Saviour. Those persons think impiously who deny that the Saints, who enjoy eternal happiness in heaven, are to be invoked; or who assert either that they do not pray for men, or that the invocation of them to pray for each of us is idolatry, or that it is repugnant to the word of God, and is opposed to the honour of the one Mediator of God and men, Jesus Christ (Sess. XXV). This had already been explained by St. Thomas:
Prayer is offered to a person in two ways: one as though to be granted by himself, another as to be obtained through him. In the first way we pray to God alone, because all our prayers ought to be directed to obtaining grace and glory which God alone gives, according to those words of the Psalm (lxxxiii, 12): ‘The Lord will give grace and glory.’ But in the second way we pray to the holy angels and to men not that God may learn our petition through them, but that by their prayers and merits our prayers may be efficacious. Wherefore it is said in the Apocalypse (viii, 4): ‘And the smoke of the incense of the prayers of the saints ascended up before God from the hand of the angel’ (Summ. Theol., II-II, Q. lxxxiii, a. 4).