Theses theologicae de sacrosancta trinitate contra antitrinitarios

LIII.
For individual persons do not differ from the whole divine essence by οὐσίᾳ essence (for as Augustine says, there is a ταυτότης identity of the divine essence in individual persons), but they differ τῷ λόγῳ by definition/reason; for example, the Father is called [Father] by one reason, namely by the reason of ἀγεννησίας unbegottenness, but He is God by another reason, namely by the reason of οὐσίας essence, which is communicable.

LIIII.
Thus, neither are the persons themselves distinguished from one another by οὐσίᾳ essence, by which reason, if the unity of the divine essence were denied, they would constitute three gods in number, which is the heresy of the Antitrinitarians, who affirm a ὁμοιότητα likeness and not a ταυτότητα identity of the divine essence in the individual persons: which error is repugnant to the Prophetic and Apostolic Scripture.

LV.
For the Prophets and Apostles acknowledge only one Jehovah, besides whom there is no other, Deut. 6, Isa. 45. Yet the same people profess the Father to be God, preach the Son as God blessed forever and true God, Rom. 9, 1 John 5, and likewise the Holy Spirit, Acts 5, 1 Cor. 12. Therefore, either there will be three gods, which is diametrically opposed to Scripture, or the Son and Holy Spirit are not true God, which Scripture denies. Or the Father, Son, and Holy Spirit are one true God in essence, differing in hypostases, which best agrees with Prophetic and Apostolic Scripture.

LVI.
Nor are those less hallucinating who assert that the Father, Son, and Holy Spirit differ only τῷ λόγῳ by definition/reason, just as one and the same man can be a doctor, a pastor, and a father of a family.

LVII.
Thus Sabellius, Samosatenus, Photinus, Marcellus, and the heretic Montanus said there is one essence and person in God, which, for the sake of time and the reason of dispensation, is sometimes called Father, sometimes Son, sometimes Holy Spirit.

LVIII.
Therefore they differ τῷ εἶναι in being, τρόπῳ ὑπάρξεως in mode of existence, and in reality, since the person of the Father is truly one thing, that of the Son another, and that of the Holy Spirit another.

LIX.
This is proven by the characteristic differences of the individuals, such as ἀγεννησία unbegottenness, γέννησις begottenness, and ἐκπόρευσις procession, which are incommunicable.

LX.
The same is shown by the apparitions in which the individual persons themselves