Epiphanius Ancoratus Chapter 6

(1) For when you are able to dare and to say that the Father was not the Father, you might also dare to sat that the Son was not the <Son>? And if you do not dare to add worth to the Father (for divinity exists immutably and is not in need of addition, nor glory, nor progress), “learn not to blaspheme.” O enemy of faith! Rather, you who drive yourself away from the faith!

(2) But you must believe always that the eternal Father truly begot the Son, the one who always really is with the Father who really is. But believe that he is the one who has been begotten.

(3) For the Son is not ever a coalescence with the Father, nor a sibling, but genuine Son who been begotten from the Father. He is natural Son, not adopted. He is Son homoousios with the Father, not sharing in essence, but homoousios, that is to say, not begotten apart from the Father, as some hold in dissimulation, wishing the Son to be so from adoption and not in truth.

(4) To say homoousios is the bond of the faith. For if you say homoousios, you destroy the power of Sebellius.

(5) For whenever (you say) homoousios it is indicative of one hypostasis, but it indicates that the Father is enhypostatic, the Son is enhypostatic, and the Holy Spirit is enhypostatic.

(6) And whenever someone says homoousios, he does not indicate that he is alien from the same divinity, but that the Son is God from God, and the Holy Spirit is called God, of the same divinity, not three gods.

(7) Nor if when we say that the Son and the Father are God, do we say two gods, for our God is one as the blessed Moses says: “The Lord your God, the Lord is one,”

(8) We do not say gods; [we say] God the Father, God the Son, God the Holy Spirit, and not gods. For there is no polytheism in God. But though the three names, the one divinity of the Father, Son and Holy Spirit <is indicated>.

(9) And there are not two sons: for the one Son is Only-begotten, and the Holy Spirit is the Spirit that is Holy, the “Spirit of God,” always existing with the Father and Son, not alien from God, but being from God, “proceeding from the Father” and “receiving from the Son.”

(10) But the Only-begotten Son is incomprehensible, and the Spirit is incomprehensible, and from God, not alien from the Father and Son. He is not coalescence of Father and Son. But the Trinity, is always of the same ousia, neither another ousia besides the divinity, nor another divinity besides the ousia, but the same divinity and from the same divinity, the Son and Holy Spirit.