2: Further, simultaneous affirmation and negation of the same things in the same respect cannot be true. But affirmation and negation are true of essence and of person. For person is distinct, whereas essence is not. Therefore person and essence are not the same.
Objection 3: Further, nothing can be subject to itself. But person is subject to essence; whence it is called "suppositum" or "hypostasis." Therefore person is not the same as essence.
On the contrary, Augustine says (De Trin. vi, 7): "When we say the person of the Father we mean nothing else but the substance of the Father."
I answer that, The truth of this question is quite clear if we consider the divine simplicity. For it was shown above ( Question [3], Article [3]) that the divine simplicity requires that in God essence is the same as "suppositum," which in intellectual substances is nothing else than person. But a difficulty seems to arise from the fact that while the divine persons are multiplied, the essence nevertheless retains its unity. And because, as Boethius says (De Trin. i), "relation multiplies the Trinity of persons," some have thought that in God essence and person differ, forasmuch as they held the relations to be "adjacent"; considering only in the relations the idea of "reference to another," and not the relations as realities. But as it was shown above ( Question [28], Article [2]) in creatures relations are accidental, whereas in God they are the divine essence itself. Thence it follows that in God essence is not really distinct from person; and yet that the persons are really distinguished from each other. For person, as above stated ( Question [29], Article [4]), signifies relation as subsisting in the divine nature. But relation as referred to the essence does not differ therefrom really, but only in our way of thinking; while as referred to an opposite relation, it has a real distinction by virtue of that opposition. Thus there are one essence and three persons.
Reply to Objection 1: There cannot be a distinction of "suppositum" in creatures by means of relations, but only by essential principles; because in creatures relations are not subsistent. But in God relations are subsistent, and so by reason of the opposition between them they distinguish the "supposita"; and yet the essence is not distinguished, because the relations themselves are not distinguished from each other so far as they are identified with the essence.
Reply to Objection 2: As essence and person in God differ in our way of thinking, it follows that something can be denied of the one and affirmed of the other; and therefore, when we suppose the one, we need not suppose the other.
Reply to Objection 3: Divine things are named by us after the way of created things, as above explained ( Question [13], Articles [1],3). And since created natures are individualized by matter which is the subject of the specific nature, it follows that individuals are called "subjects," "supposita," or "hypostases." So the divine persons are named "supposita" or "hypostases," but not as if there really existed any real "supposition" or "subjection."
Whether it must be said that the three persons are of one essence?
Objection 1: It would seem not right to say that the three persons are of one essence. For Hilary says (De Synod.) that the Father, Son and Holy Ghost "are indeed three by substance, but one in harmony." But the substance of God is His essence. Therefore the three persons are not of one essence.
Objection 2: Further, nothing is to be affirmed of God except what can be confirmed by the authority of Holy Writ, as appears from Dionysius (Div. Nom. i). Now Holy Writ never says that the Father, Son and Holy Ghost are of one essence. Therefore this should not be asserted.
Objection 3: Further, the divine nature is the same as the divine essence. It suffices therefore to say that the three persons are of one nature.
Objection 4: Further, it is not usual to say that the person is of the essence; but rather that the essence is of the person. Therefore it does not seem fitting to say that the three persons are of one essence.
Objection 5: Further, Augustine says (De Trin. vii, 6) that we do not say that the three persons are "from one essence [ex una essentia]," lest we should seem to indicate a distinction between the essence and the persons in God. But prepositions which imply transition, denote the oblique case. Therefore it is equally wrong to say that the three persons are "of one essence [unius essentiae]."
Objection 6: Further, nothing should be said of God which can be occasion of error. Now, to say that the three persons are of one essence or substance, furnishes occasion of error. For, as Hilary says (De Synod.): "One substance predicated of the Father and the Son signifies either one subsistent, with two denominations; or one substance divided into two imperfect substances; or a third prior substance taken and assumed by the other two." Therefore it must not be said that the three persons are of one substance.
On the contrary, Augustine says (Contra Maxim. iii) that the word {homoousion}, which the Council of Nicaea adopted against the Arians, means that the three persons are of one essence.
I answer that, As above explained ( Question [13], Articles [1],2), divine things are named by our intellect, not as they really are in themselves, for in that way it knows them not; but in a way that belongs to things created. And as in the objects of the senses, whence the intellect derives its knowledge, the nature of the species is made individual by the matter, and thus the nature is as the form, and the individual is the "suppositum" of the form; so also in God the essence is taken as the form of the three persons, according to our mode of signification. Now in creatures we say that every form belongs to that whereof it is the form; as the health and beauty of a man belongs to the man. But we do not say of that which has a form, that it belongs to the form, unless some adjective qualifies the form; as when we say: "That woman is of a handsome figure," or: "This man is of perfect virtue." In like manner, as in God the persons are multiplied, and the essence is not multiplied, we speak of one essence of the three persons, and three persons of the one essence, provided that these genitives be understood as designating the form.
Reply to Objection 1: Substance is here taken for the "hypostasis," and not for the essence.
Reply to Objection 2: Although we may not find it declared in Holy Writ in so many words that the three persons are of one essence, nevertheless we find it so stated as regards the meaning; for instance, "I and the Father are one (Jn. 10:30)," and "I am in the Father, and the Father in Me (Jn. 10:38)"; and there are many other texts of the same import.
Reply to Objection 3: Because "nature" designates the principle of action while "essence" comes from being [essendo], things may be said to be of one nature which agree in some action, as all things which give heat; but only those things can be said to be of "one essence" which have one being. So the divine unity is better described by saying that the three persons are "of one essence," than by saying they are "of one nature."
Reply
