As long as Christ, “the Master and the Lord (ὁ διδάσκαλος καὶ ὁ Κύριος)” (John 13:13), remained visibly on earth, there was no room or need for any other visible head. But since He willed that His kingdom should be visible, He was obliged, when He ascended into heaven, to designate a vicegerent on earth. “Should any one say that Christ is the one Head and the one Shepherd, the one Spouse of the one Church, he does not give an adequate reply. It is clear, indeed, that Christ is the author of grace in the sacraments of the Church; it is Christ Himself who baptizes; it is He who forgives sins; it is He who is the true Priest, who offered Himself upon the altar of the Cross; and it is by His power that His Body is daily consecrated upon the altar; and, still, because He was not visibly present to all the faithful, He made choice of ministers through whom the aforesaid sacraments should be dispensed to the faithful.… For the same reason, therefore, because He was about to withdraw His visible presence from the Church, it was necessary that He should appoint some one in His place to have the charge of the Universal Church. Hence, before His ascension He said to Peter, ‘Feed My sheep’ “ (St. Thomas, Contra Gentiles, lib. iv. cc. 74, 76).