On God

Question 1

On God

There were questions concerning God, (Q. 1.) angels, (Q. 2.) man, (Qq. 3–10.) and purely bodily creatures. (Q. 11.)

Article 1

Whether unity of essence is added in number with unity of person

About God one thing was asked, namely, whether unity of essence is added in number with unity of person. And it seems that it is not.

Obj. 1: For there are three divine persons. If, therefore, unity of essence were to be added in number with unity of person, it would follow that in God there is quaternity, which is heretical. Therefore, unity of essence is not added in number with unity of person.

On the contrary (2): If unity of essence were utterly the same as unity of person, not being added with it in number, then it would follow that where one is predicated of something, the rest would be predicated also. But unity of essence is predicated of the three persons: for we say that Father and Son and Holy Spirit are one. Therefore, personal unity also will be predicated of them, saying that Father and Son and Holy Spirit are one, which is clearly false.

I answer that each one, inasmuch as it is one, is a being; hence being and one are convertible. (Aristotle, Metaphysics 4.2, 1003b22–25; 10.2, 1054a13–19; Boethius, On the Person and the Two Natures: A Treatise Against Eutyches and Nestorius, ch. 4 (PL 64:1346).) Yet each one is a being through its form. (Cf. Boethius, On the Trinity, ch. 2 (PL 64:1250–51).) Hence also each one through its form has unity. And thence it is that the comparison of form to form is the same as the comparison of unity to unity. Yet God is formally God through his essence; yet personal property is as though a form constituting a person, which indeed is distinguished really from another person on account of relative opposition. But personal property is not distinguished really from essence; otherwise, it would follow that in God there is composition and that something comes to him through the mode of an accident: for everything which is outside the essence of a thing comes to it accidentally. Nevertheless, personal property differs from essence according to the mode of understanding and of signifying: for essence is said absolutely, whereas personal property implies relation. Hence it is clear that unity of person is not added in number with unity of essence as though really differing from it, but only according to the mode of understanding.

Reply Obj. 1: And through this the response to the objections is clear. For the first proceeded according to the difference of the thing, yet because this does not exist in divine matters between unity of essence and person, quaternity cannot be posited in God.

Reply Obj. 2: Whereas the second proceeded according to the difference which is from the mode of understanding and of signifying, whereby we say that Father and Son and Holy Spirit are one, but not one.