Hilary of Poitiers — as excerpted in the Catena Aurea on Matthew 28:16-20

“(de Trin. ii. 1 &c.) For what part of the salvation of men is there that is not contained in this Sacrament? All things are full and perfect, as proceeding from Him who is full and perfect. The nature of His relation is expressed in the title Father; but He is nothing but Father; for not after the manner of men does He derive from somewhat else that He is Father, being Himself Unbegotten, Eternal, and having the source of His being in Himself, known to none, save the Son. The Son is the Offspring of the Unbegotten, One of the One, True of the True, Living of the Living, Perfect of the Perfect, Strength of Strength, Wisdom of Wisdom, Glory of Glory; the Image of the Unseen God, the Form of the Unbegotten Father. Neither can the Holy Spirit be separated from the confession of the Father and the Son. And this consolation of our longing desires is absent from no place. He is the pledge of our hope in the effects of His gifts, He is the light of our minds, He shines in our souls. These things as the heretics cannot change, they introduce into them their human explanations. As Sabellius who identifies the Father with the Son, thinking the distinction to be made rather in name than in person, and setting forth one and the same Person as both Father and Son. As Ebion, who deriving the beginning of His existence from Mary, makes Him not Man of God, but God of man. As the Arians, who derive the form, the power, and the wisdom of God out of nothing, and in time. What wonder then that men should have diverse opinions about the Holy Spirit, who thus rashly after their own pleasure create and change the Son, by whom that Spirit is bestowed?”