Hilary says (De Trin. iv): "The Son has nothing else than birth." But He is Son by "birth." Therefore, if filiation be removed, the Son's hypostasis no more remains; and the same holds as regards the other persons.
I answer that, Abstraction by the intellect is twofold---when the universal is abstracted from the particular, as animal abstracted from man; and when the form is abstracted from the matter, as the form of a circle is abstracted by the intellect from any sensible matter. The difference between these two abstractions consists in the fact that in the abstraction of the universal from the particular, that from which the abstraction is made does not remain; for when the difference of rationality is removed from man, the man no longer remains in the intellect, but animal alone remains. But in the abstraction of the form from the matter, both the form and the matter remain in the intellect; as, for instance, if we abstract the form of a circle from brass, there remains in our intellect separately the understanding both of a circle, and of brass. Now, although there is no universal nor particular in God, nor form and matter, in reality; nevertheless, as regards the mode of signification there is a certain likeness of these things in God; and thus Damascene says (De Fide Orth. iii, 6) that "substance is common and hypostasis is particular." So, if we speak of the abstraction of the universal from the particular, the common universal essence remains in the intellect if the properties are removed; but not the hypostasis of the Father, which is, as it were, a particular.
But as regards the abstraction of the form from the matter, if the non-personal properties are removed, then the idea of the hypostases and persons remains; as, for instance, if the fact of the Father's being unbegotten or spirating be mentally abstracted from the Father, the Father's hypostasis or person remains.
If, however, the personal property be mentally abstracted, the idea of the hypostasis no longer remains. For the personal properties are not to be understood as added to the divine hypostases, as a form is added to a pre-existing subject: but they carry with them their own "supposita," inasmuch as they are themselves subsisting persons; thus paternity is the Father Himself. For hypostasis signifies something distinct in God, since hypostasis means an individual substance. So, as relation distinguishes and constitutes the hypostases, as above explained ( Article [2]), it follows that if the personal relations are mentally abstracted, the hypostases no longer remain. Some, however, think, as above noted, that the divine hypostases are not distinguished by the relations, but only by origin; so that the Father is a hypostasis as not from another, and the Son is a hypostasis as from another by generation. And that the consequent relations which are to be regarded as properties of dignity, constitute the notion of a person, and are thus called "personal properties." Hence, if these relations are mentally abstracted, the hypostasis, but not the persons, remain.
But this is impossible, for two reasons: first, because the relations distinguish and constitute the hypostases, as shown above ( Article [2]); secondly, because every hypostasis of a rational nature is a person, as appears from the definition of Boethius (De Duab. Nat.) that, "person is the individual substance of a rational nature." Hence, to have hypostasis and not person, it would be necessary to abstract the rationality from the nature, but not the property from the person.
Reply to Objection 1: Person does not add to hypostasis a distinguishing property absolutely, but a distinguishing property of dignity, all of which must be taken as the difference. Now, this distinguishing property is one of dignity precisely because it is understood as subsisting in a rational nature. Hence, if the distinguishing property be removed from the person, the hypostasis no longer remains; whereas it would remain were the rationality of the nature removed; for both person and hypostasis are individual substances. Consequently, in God the distinguishing relation belongs essentially to both.
Reply to Objection 2: By paternity the Father is not only Father, but is a person, and is "someone," or a hypostasis. It does not follow, however, that the Son is not "someone" or a hypostasis; just as it does not follow that He is not a person.
Reply to Objection 3: Augustine does not mean to say that the hypostasis of the Father would remain as unbegotten, if His paternity were removed, as if innascibility constituted and distinguished the hypostasis of the Father; for this would be impossible, since "being unbegotten" says nothing positive and is only a negation, as he himself says. But he speaks in a general sense, forasmuch as not every unbegotten being is the Father. So, if paternity be removed, the hypostasis of the Father does not remain in God, as distinguished from the other persons, but only as distinguished from creatures; as the Jews understand it.
Whether the properties presuppose the notional acts?
Objection 1: It would seem that the notional acts are understood before the properties. For the Master of the Sentences says (Sent. i, D, xxvii) that "the Father always is, because He is ever begetting the Son." So it seems that generation precedes paternity in the order of intelligence.
Objection 2: Further, in the order of intelligence every relation presupposes that on which it is founded; as equality presupposes quantity. But paternity is a relation founded on the action of generation. Therefore paternity presupposes generation.
Objection 3: Further, active generation is to paternity as nativity is to filiation. But filiation presupposes nativity; for the Son is so called because He is born. Therefore paternity also presupposes generation.
On the contrary, Generation is the operation of the person of the Father. But paternity constitutes the person of the Father. Therefore in the order of intelligence, paternity is prior to generation.
I answer that, According to the opinion that the properties do not distinguish and constitute the hypostases in God, but only manifest them as already distinct and constituted, we must absolutely say that the relations in our mode of understanding follow upon the notional acts, so that we can say, without qualifying the phrase, that "because He begets, He is the Father." A distinction, however, is needed if we suppose that the relations distinguish and constitute the divine hypostases. For origin has in God an active and passive signification---active, as generation is attributed to the Father, and spiration, taken for the notional act, is attributed to the Father and the Son; passive, as nativity is attributed to the Son, and procession to the Holy Ghost. For, in the order of intelligence, origin, in the passive sense, simply precedes the personal properties of the person proceeding; because origin, as passively understood, signifies the way to a person constituted by the property. Likewise, origin signified actively is prior in the order of intelligence to the non-personal relation of the person originating; as the notional act of spiration precedes, in the order of intelligence, the unnamed relative property common to the Father and the Son. The personal property of the Father can be considered in a twofold sense: firstly, as a relation; and thus again in the order of intelligence it presupposes the notional act, for relation, as such, is founded upon an act: secondly, according as it constitutes the person; and thus the notional act presupposes the relation, as an action presupposes a person acting.
Reply to Objection 1: When the Master says that "because He begets, He is Father," the term "Father" is taken as meaning relation only, but not as signifying the subsisting person; for then it would be necessary to say conversely that because He is Father He begets.
Reply to Objection 2: This objection avails of paternity as a relation, but not as constituting a person.
Reply to Objection 3: Nativity is the way to the person of the Son; and so, in the order of intelligence, it precedes filiation, even as constituting the person of the Son. But active generation signifies a proceeding from the person of the Father; wherefore it presupposes the personal property of the Father.
