Commentaria in Summam contra Gentiles, Liber II

After St. Thomas has excluded matter from intellectual substances with respect to their essence, he now excludes from them matter with respect to their dependence, as regards esse, upon matter ¹.

I. And he posits this conclusion: Intellectual natures are subsistent forms, but they do not exist in matter as though their esse depended on matter.

First proof. If this were so, the natures themselves would not properly have esse, but only the composites. Therefore they would have material esse, just as if they were composed of matter and form: namely, because their esse would properly be the esse of a thing composed of matter and form, like the esse of the composite. But this is false. Therefore, and so on.

Second. They would not act of themselves, but composites would act through them. Therefore they would not understand, but composites made up of them and matter. Therefore the intellect would be composed of matter and form.

Note that Saint Thomas speaks of the intellectual nature insofar as it is intellectual, and which is wholly intellectual. Of this it is true that, if it did not understand through itself but as composed, the intellectual nature, insofar as it is intellectual, would have to be composed of matter and form: for the intellectual nature is that to which understanding belongs first and of itself as a whole, just like that which understands. And Saint Thomas signified this by inferring that the intellect ² would be composed of matter and form: by intellect he meant not the intellective power, but the nature which is wholly intellectual.

Third. That which is received in the intellect would be received in matter. This is false. Therefore, etc. — The consequence is proved. Because forms which have their esse in matter bound ³, that is, immersed in matter and dependent upon it, do not receive anything that is not received in matter: as is evident in bodily powers fixed to organs.

II. Fourth. The intellect is not composed of matter and form. Therefore it is not a material form. — The consequence is proved: because to say that the intellect is a form immersed in matter is, in reality, the same as saying that it is composed of matter and form; there is only a difference in name. For in the first way, that is, by saying that the intellect is the form of matter immersed, the intellect would be said to be the very form of the composite; but in the second way, that is, by saying that the intellect is composed of matter and form, the intellect would be said to be the composite itself; and thus form and composite would be distinguished only by name.

Note that Saint Thomas says for this reason that esse, in the sense of understood being, is the same thing in reality as the form immersed in matter, and as the very thing composed from form and matter, because in both ways the intellectual nature, considered thus, is said to depend on matter both in its esse and in its operation. For just as the form immersed in matter, so also the composite of matter and a form so immersed in matter, depends on matter both in its esse and in its acting.

Second, we may also interpret this as follows: namely, that not only the form of the composite would be called intellect, that is, a purely intellectual nature, but also the composite itself. For from the union of a merely and purely intellectual form with matter there would result a composite that would be of a merely and purely intellectual nature; just as, because the intellective soul is also sensitive and vegetative, and not only intellective, there results from its union with matter a nature that is not merely intellective but also sensitive and vegetative. Since, therefore, it is false that a merely intellectual nature is composed of matter and form, as was shown above ⁴, it follows most fittingly that the intellect is not a form immersed in matter. — And this interpretation seems to be more in accord with the mind of St. Thomas.