Psalms 71:18

Hear now also the Son's statements about the Father: "The Spirit of the Lord is on me, because he has anointed me to preach the gospel to the poor." He speaks of himself likewise to the Father in the psalm: "Forsake me not, until I have declared the might of your arm to all the generations that are to come." Also with the same substance in another psalm: "O Lord, how many are they that trouble me!" But almost all the psalms that prophesy of the person of Christ, represent the Son as conversing with the Father—that is, represent Christ [as speaking] to God. Observe also the Spirit speaking of the Father and the Son, in the character of a third person: "The Lord said to my Lord, Sit on my right hand, until I make your enemies your footstool." Likewise in the words of Isaiah: "Thus says the Lord to the Lord my anointed."

"And even unto oldness and old age." These are two terms for old age, and are distinguished by the Greeks. For the gravity succeeding youth hath another name among the Greeks, and after that same gravity the last age coming on hath another name; for πρεσβύτης signifieth grave, and γέρων old. But because in the Latin language the distinction of these two terms holdeth not, both words implying old age are inserted, oldness and old age: but ye know them to be two ages. "Thou hast taught me Thy grace from my youth; and even until now;" after my youth, "I will tell forth Thy wonderful works," because Thou art with me in order that I may not die, who hast come in order that I may rise: "and even unto oldness and old age," that is, even unto my last breath, unless with me Thou shalt have been, there will not be any merit of mine; may Thy grace alway remain with me. Even one man would say this, thou, he, I; but because this voice is that of a certain great Man, that is, of the Unity itself, for it is the voice of the Church; let us investigate the youth of the Church. When Christ came, He was crucified, dead, rose again, called the Gentiles, they began to be converted, became Martyrs strong in Christ, there was shed faithful blood, there arose a harvest for the Church: this is Her youth. But seasons advancing let the Church confess, let Her say, "Even until now I will tell forth Thy wonderful works." Not only in youth, when Paul, when Peter, when the first Apostles told: even in advancing age I myself, that is, Thy Unity, Thy members, Thy Body, "will tell forth Thy marvellous works." What then? "And even unto oldness and old age," I will tell forth Thy wonderful works: even until the end of the world here shall be the Church. For if She were not to be here even unto the end of the world; to whom did the Lord say, "Behold, I am with you always, even unto the consummation of the world"? Why was it necessary that these things should be spoken in the Scriptures? Because there were to be enemies of the Christian Faith who would say, "for a short time are the Christians, hereafter they shall perish, and there shall come back idols, there shall come back that which was before. How long shall be the Christians?" "Even unto oldness and old age:" that is, even unto the end of the world. When thou, miserable unbeliever, dost expect Christians to pass away, thou art passing…