Commentaria in Primam Partem Summae Theologiae

In the title, the trinity is taken according to the proper signification of the word.

In the body there is a single conclusion, answering affirmatively: the name of Trinity is to be used of God. – And it is proved thus. In God there is posited a plurality of persons; therefore there must also be posited a trinity of those same persons. The consequence is proved: because what plurality signifies indeterminately, trinity signifies determinately; for it imports a determined number, namely threefold. – And this argument proceeds, supposing the truth of faith, namely that in God there are truly three Persons.

In this title, and in the following questions of this question, the inquiry concerns these terms according to their proper significations, such that they yield true and sound propositions, for instance: The Son is other than the Father, etc.

II. In the body he does four things. First, he shows the manner to be observed in speaking of the Trinity: namely, cautiously and modestly. – And he explains this in two ways. First in general, by the authorities of Jerome and Augustine. Second in particular, on account of the extreme errors of Arius and Sabellius.

Second, he says that four names are to be avoided on account of Arius: namely, diversity, division, disparity, and alien.

Third, four terms must likewise be avoided on account of Sabellius: namely, singularis, unici, confusi, and solitarii.

Fourth, he answers the question affirmatively: The Son is other than the Father. – And he proves this as follows. "Other", taken in the masculine, signifies nothing but the distinction of the supposit; therefore. The consequence is proved: because the Son is another supposit of the divine nature. Which is evident from the equivalent expression: namely, because he is another person and another hypostasis.

That a distinction holds in the divine persons, as the deduction in the body of the article supposes, is proved from the nature of relative opposition.

The title is clear enough for intelligent readers. In the body three things are said. First, it is distinguished that the word alone can be taken in two ways, namely as a categorematic and as a syncategorematic term: and the members are explained clearly enough in the text. — Next, one conclusion is laid down answering the question negatively, namely: Alone taken categorematically cannot be added to an essential term in the divine. It is proved: because it would follow that God is solitary. — Then the other conclusion is laid down affirmatively: Alone taken syncategorematically can be added to an essential term in the divine. And it is proved: because the others can thereby be excluded from sharing in the predicate; as is evident in saying, God alone is eternal.

The title is limited: for the question is not whether an exclusive term can be added to a personal term, say to the Father, absolutely; but with respect to a common predicate, say to live, to understand, to be, etc.

II. In the body he answers the question with four conclusions and a corollary. He arranged them with the following artifice. First, he took one proposition, in which an exclusive word is added to a personal term with respect to a common predicate, so that in it the others may be clearly seen, namely: only the Father is God. Then he distinguished four senses of the same, by distinguishing the word only in several ways: and alongside each sense he set each conclusion. The distinction is as follows. The word only is taken in two ways: categorematically, and thus the proposition is false, because it posits the Father as solitary; syncategorematically, and then in two ways. Either it excludes from the subject's form: and thus it is true but improper; true indeed, on the authority of Augustine; improper, however, because not except with an implicit understanding. Or it excludes from the company of the predicate, and this in two ways: namely, either in the masculine, and thus it is false and proper; or neutrally, and thus it is true but improper. And both are proved, with respect to being taken properly and improperly, because only properly regards the subject, and more excludes what is another than what is something else; but with respect to truth and falsity, because the Son, and likewise the Holy Spirit, is another than the Father, and not something else; for whatever is another must be created.

The corollary, however, is that propositions of this kind, being improper, are not to be extended, but are to be expounded piously.