Commentaria in Primam Partem Summae Theologiae

In the title, note the terms. the ratio of good: not universally, but of caused being, as is clear in the following article¹; for in God these have no place. And again the ratio of good, not in any way whatever, but of good as that by which. – Mode, species, and order. St. Thomas is found to have used these terms in three ways. Here indeed, in the body, by mode he means the commensuration of the efficient principles, or material ones; by species, form; by order, inclination toward something. But in Ia IIae, qu. LXXXV, art. 4, by species he means form absolutely; by mode, the measure of the form itself (for the species of things are measured like numbers); but by order, a respect toward another. In the question De Veritate, however, qu. XXI², he means by species form; by mode, the commensuration of esse itself to the essence to which it belongs; but by order, a respect with regard to what perfects finally, closed within the ratio of good. – These three expositions, although they may seem to differ greatly with respect to one term, namely "mode"; yet if we examine them more subtly, they converge into one. For the commensuration of principles, the measure of form, and the commensuration of esse to essence mutually imply one another. For from such a harmony of principles there is a form of such perfection; and from so great a form, so much esse, according to the order of generation. But according to the order of perfection or end, if esse of such perfection is to be produced, then a form and essence of such perfection must be supposed; and if this, then such a disposition of the preceding principles.

The reason of the good as consisting in mode, species, and order can be understood in two ways. In one way, as in the essential parts, just as the reason of man consists in animal and rational. In another way, as in the integral parts, not of the reason itself, but of its proper matter, just as the reason of man consists in flesh, bones, and sinews. And it is in this way that I understand in the present case the reason of the good to consist in mode, species, and order. – The sense of the title, therefore, is: Whether the reason of the good as that which, being caused, consists in form, antecedents, and consequents, as in the parts of its proper matter.

II. In the body, a single conclusion, answering the question affirmatively: The ratio of good consists in mode, species, and order. – It is proved. Each thing is what it is through its form, which requires certain antecedents and consequents. Therefore, that to which nothing is lacking according to the mode of its nature has species, mode, and order. Therefore, the perfect being has these. Therefore, good requires these. – The antecedent is evident on both counts. The first consequence is evident from the quiddity of the term of species, mode, and order. The second holds by the argument from definition to the thing defined. The third, however, is proved: because perfection is the ratio of the appetible.

III. Concerning this conclusion a doubt arises: how can the mode in the substantial good of the angels be preserved, when mode, that is, the commensuration of the efficient principles, or of the material ones, is explained as it is said here; since in the angels there are no material principles, and their efficient cause is God alone, whose action is His very substance.

To this it is briefly said that, according to the exposition set forth in this place, the mode of the good angel is saved with respect to substance, as regards the efficient principle, thus. For God as agent can be taken in two ways. In one way, absolutely: and so both He Himself and His action are above every mode. In another way, as acting according to this or that idea: and so God's action is commensurate to this thing, not to another; just as the idea is so properly the idea of this thing, that it is not of another. And in this way the productive action of Gabriel is modified, and modifies the esse and substantial goodness of Gabriel: and this suffices. – The mode can also be saved in angels according to the material principle: since essence is as matter for its esse, and is commensurate to it. But this pertains more to the other expositions³: since here the mode precedes the form, as is clear from the text.