Chapter 15 — That it is necessary for God to be one

Hence the conclusion is also evident that there can only be one God. If there were many gods, they would be called gods either equivocally or univocally. If they are called gods equivocally, this is not relevant to our topic: there is nothing to prevent other peoples from applying the name ‘god’ to what we call a stone. If they are called gods univocally, they must agree either in genus or in species. But we have just shown that God can be neither a genus nor a species comprising many individuals under itself. Accordingly, a multiplicity of gods is impossible.

Again, that whereby a common essence is individuated cannot pertain to many. Although there can be many men, it is impossible for this particular man to be more than one only. So if an essence is individuated by itself, and not by something else, it cannot pertain to many. But the divine essence is individuated by itself, since God’s essence is not distinct from his existence; for we have shown that God is his essence. Hence God cannot be more than one only.

Again, a form can be multiplied in two ways: first, by specific differences, as in the case of a generic form; this is how color is differentiated into the various species of color. Second, by the subjects in which it inheres, as whiteness is multiplied. Therefore, any form incapable of being multiplied by specific differences, if it is a form that does not exist in a subject, cannot be multiplied at all. Thus whiteness, if it were to subsist without a subject, would not be more than one. But the divine essence is being itself, which does not admit of specific differences, as we have shown. Since, therefore, the divine existence is like a form subsisting by itself (for God is his existence), the divine essence cannot be more than one. Accordingly, a plurality of gods is impossible.