Father Pegues writes: “The consequences of the Incarnation were that Christ was subject to the Father; that He prayed; that He served God the Father by His priesthood.”
Concerning Christ’s subjection to His Father: “He was subject to the Father by reason of His human nature because this had only participated goodness, whereas the Father is goodness by essence; hence whatever was related to Christ’s human life was ruled, disposed, and ordered by the Father. In Christ there was the most perfect and absolute obedience in respect of the Father.”
Christ prayed to God the Father: “The human will being incapable of attaining the fulfilment of its desires independently of the divine will, Christ as man had perforce to address the Father in order that the Father by His all-powerful will might accomplish what the human will was unable to realize of itself.” He prayed, not only for others, but also for Himself: “He prayed for the external glorification of His Body which He had not so long as He was on earth; also in order to give thanks to the Father for all the gifts and privileges bestowed upon His human nature.” His prayers were always answered because “Christ, who knew perfectly the will of His Father, never wished anything deliberately except what He knew to be in conformity with His Father’s will.”
Christ is a priest because “it belonged to Him, par excellence, to bring to men the gifts of God; and to stand before God in the name of men to offer their prayers to God to appease Him and to re-establish them in His favour.” He is both priest and victim because “in accepting death for our sakes he became a victim in the threefold sense of sacrifice as established by the Old Law, namely, a victim of sin, a victim of peace, and a holocaust. He has, in fact, made satisfaction for our sins and has blotted them out; He has obtained for us the grace of God which is our peace and salvation; and He has opened for us the gates of heaven.” His priesthood will last forever “in the sense that the effect of His priesthood which is the possession of heaven, will remain always, for the attainment of heaven by the blessed is the consummation of Christ’s sacrifice.”
Quotations from Thomas Pegues, Catechism of the “Summa Theologica” of Saint Thomas Aquinas, trans. Aelred Whitacre (New York: Benziger, 1922).