I cannot sum up all this testimony of Scripture better than in the grand, concise language of Bossuet, in his sermon on the Unity of the Church:

"Peter appears in every respect as the first: the first to confess the faith; the first in the manifestation of love; the first of all the Apostles who saw the Saviour raised from the dead, as he was the first witness of the fact before all the people; the first, when it was necessary to fill up the number of the Apostles; the first who confirmed the faith by a miracle; the first to convert the Jews; the first to receive the Gentiles; the first everywhere. It is impossible for me to mention every proof. Everything concurs to establish his primacy; yes, even his very faults. When power is given to several, the exercise of the power by each one is restricted by the fact that others share it with him. But power given to a single individual over all, and without exception, necessarily implies the plenitude of power. … All the apostles receive the same power, but not in the same degree, or with the same extent. Jesus Christ commences by the first, and in this first one He develops the whole, in order that we may learn that the ecclesiastical authority which was originally constituted in the person of one man is not imparted to others, except on the condition of remaining always subordinate to the principle from which its unity is derived, and that all those who shall be charged with its exercise are found to remain inseparably united to the same chair."

This is enough to show what some of the most eminent Protestant writers even have acknowledged, that St. Peter was the first, the chief, the most pre-eminent, the Prince of the Apostles. St. Peter was also the Vicar of Jesus Christ, the Supreme Pastor and Ruler of the Church.

The title of Vicar of Christ implies that Jesus Christ delegated to him His own jurisdiction over the Church. A vicar is one who exercises the authority vested in the principal by delegation from him. A viceroy or vice-king governs a subordinate kingdom, vice regis, in place of the king. A vicar-general exercises episcopal jurisdiction, vice episcopi, in place of the bishop, and governs the diocese during his absence. So when St. Peter is said to have been made by our Lord His Vicar, it means that he received jurisdiction to govern in the place of Jesus Christ Himself, Who is by personal and inherent right the High Priest of the Catholic Church, but Who, being absent from the earth, must exercise His functions by a substitute. It is unquestionable that, under the Old Law, the high-priest was the vice gerent of God, and the supreme head of the Jewish Church. It is equally unquestionable that, in establishing the New Law, Christ appointed St. Peter His Vicar and the Supreme Head of the Christian Church. There is nothing clearer in the New Testament than this. Jesus Christ distinctly promised to St. Peter that He would build His Church upon him, and would give him the keys of the kingdom of heaven; and He actually fulfilled these promises before He ascended into heaven, by committing His universal flock to him alone to feed and rule it. This promise is recorded in the sixteenth chapter of St. Matthew's Gospel:

"Jesus saith to them: But whom do you say that I am? Simon Peter answered and said: Thou art Christ the Son of the living God. And Jesus answering, said to him: Blessed art thou, Simon Bar-Jona: because flesh and blood hath not revealed it unto thee, but My Father who is in heaven. And I say to thee: That them art Peter; and upon this rock I will build My Church, and the gates of hell shall not prevail against it. And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven; and whatsoever thou shalt loose on earth, it shall be loosed also in heaven."

In this magnificent promise, Jesus Christ evidently declares His intention to delegate supreme power to St. Peter, and constitute him His Vicar in the Christian Church.

This supreme power is signified by a double metaphor, viz., a foundation and keys. First, He says: "Thou art Peter; and on this rock I will build My Church." In order to understand the force of this declaration, it is necessary to call to mind that the name of Peter, which signifies Rock, was not the proper name of the Apostle. His name was Simon. The Lord gave him the name of Peter when He first called him to the apostleship, as an appellation significant of his character and office in the Church. But it was on the occasion of his noble confession of Christ, made by a special inspiration of the Holy Ghost, that He first announced the full import of that mysterious name. St. Peter said, "Thou art Christ"—by this title, which signifies the Anointed One, acknowledging all those divine attributes and prerogatives which are implied in the character of the Messiah of God and Redeemer of the world. The Lord replied in a manner denoting the solemnity of the occasion, and speaking with all the dignity and authority of a Legislator and a Prophet, by conferring on St. Peter, in return for the honor which he had just rendered Him, the highest honor which was in His gift: "Thou art Peter [i.e., a Rock]: and on this Rock I will build My Church." The plain and natural sense of these words of Christ is, that He appoints Peter to occupy a position in the spiritual edifice of the Church corresponding to that occupied by a foundation in a material building. The foundation sustains and, as it were, rules the whole edifice—i.e., by its strength it keeps the whole building in order, and every portion of it in its proper place, thus keeping it from crumbling into ruin—and losing all structural form in a mass of shattered fragments. The foundation is to the building the principle of its unity, repose, order, and durability. Therefore, Peter must be the same to the Church. By him the Church must be sustained, ruled, kept in order, and prevented from falling in pieces, and thus losing its organic form. His authority must be the principle of its unity, strength, and perpetuity. All the force of its laws must be derived from him, and all its authority must ultimately rest on him as its final ground and basis. This is the first portion of our Lord's divine decree concerning St. Peter. Let us now examine the second.

"I will give to thee the keys of the kingdom of heaven." Among the principal nations of antiquity, and particularly among the Hebrews, it was a received usage that the tradition of the keys denoted the transfer or acknowledgment of supreme power over the house, citadel, or city to whose gates they belonged. These keys, when made of precious metal, and, as was often the case, richly ornamented, were a symbol of power and dignity, and carried only by kings, princes, and magistrates. In the Hebrew monarchy, the chief of the royal household, who was a kind of grand chancellor of the kingdom, or vicar of the king, carried a large key on his shoulder as a badge of his office. In the Prophecy of Isaias,[C. xxii.] we read this prediction concerning Eliacim, son of the high-priest Helcias: "I will place upon his shoulder the key of the house of David, and he shall open and there shall be no one who shall shut, and he shall shut and there shall be no one who shall open, and he shall be on the throne of glory of his father's house."