Appendix 21.

(622) [The action of St. Thomas' acting intellect]

I would like to add a few more words about St. Thomas' teaching. It is important that the philosophical principles on which he bases religious teaching, so profoundly needed by human nature, should be understood perfectly.

I have already noted that the intellect cannot be the power which universalises sensations; only the soul can do this through its unity and simplicity. On the one hand, the soul experiences sensations; on the other, it possesses the vision of being and unites these two things in itself. If we examine the use made of the acting intellect by St. Thomas, we shall see that the power of the soul uniting these two things is what he calls the acting intellect. Consequently, the acting intellect corresponds to what I have called the faculty of primal synthesis or the first function of reason. St. Thomas also notes a particular reason, which he calls the cogitative force, whose power lies in descending to particular matters and regulating them: mens regit inferiores, et sic singularibus se immiscet movente ratione particulari, quae est potentia quaedam individualis quae alio nomine dicitur cogitativa [The mind governs the inferior faculties, and thus influences individual things with its own particular reasoning power, that is, with a certain individual potency we call cogitative] (De Ver., q. 10, art. 5).

As he says, reason is the power of the soul that, after coming into possession of sensations and phantasms on the one side, and possession of ens on the other, joins these two extremes. This energy of the soul then becomes St. Thomas' particular reason or cogitative force when considered relative to the particulars which it has to regulate. But if it is considered as a power for forming ideas in the way described, that is, by universalising phantasms, then it corresponds to St. Thomas' acting intellect which he rightly calls virtus quaedam animae nostrae [a certain power of our soul] (S.T., I, q. 89, art. 4). St. Thomas' teaching will be understood more clearly if we are allowed the following observations.

St. Thomas first establishes that neither sensations as such nor corporeal images (phantasmata) are ideas; the acting intellect has to illustrate them in order to render them such. I have already shown how this illustration, or illumination, is simply their universalisation brought about by adding to them the light of the acting intellect, that is, possibility or ideal being. The soul considers the sensations it experiences as infinitely renewable, and hence views them in their possible or general existence, rather than in their individual existence. Formae sensibiles non possunt agere in mentem nostram, nisi quatenus per lumen intellectus agentis immateriales redduntur, et sic efficiuntur quodammodo homogeneae intellectui possibili, in quem agunt [Sensible forms cannot act relatively to our mind unless they are rendered immaterial through the light of the acting intellect and thus made compatible with the possible intellect in which they act] (De Ver., q. 10, art. 6). He concludes that the principal agent in the formation of ideas is neither sense nor phantasms, but the acting intellect with its innate light.

My own comment is this. If the acting intellect renders the phantasms immaterial (universalises them), it must act upon them and, according to St. Thomas' own phrase, 'turn towards them'. The acting intellect, therefore, can only be the power possessed by the soul of beholding, in possible being which it intuits, the sensations it experiences. The following passage shows clearly that the nature of the acting intellect is as I have described it. St. Thomas shows that the acting intellect makes phantasms immaterial. This takes place through the unity of the subject, that is, of the soul which on the one side has the phantasms, on the other the power of the intellect. He says: 'Although the intellective soul is immaterial in act, it is in potency to DETERMINATE species of things.' This immateriality in act on the part of the intellective soul indicates its intuition of being in a universal act, free from corporeal limitations and determinations. St. Thomas does in fact teach that we know the immateriality of the soul by its ideas which we find to be universal (De Ver., q. 10, art. 8) and therefore immaterial. He continues: 'The phantasms, although certainly likenesses of some species in act, are only potentially immaterial', that is, they are not universal, although they can be universalised by our spirit. 'There is nothing to prevent a SINGLE, IDENTICAL SOUL which is immaterial in act', that is, in so far as it has the idea of possible being, 'from possessing a certain power enabling it to render immaterial in act (to universalise) the phantasms by abstracting from the individual conditions imposed by matter. THIS POWER IS CALLED THE ACTING INTELLECT. At the same time, the one, identical soul may possess another receptive power called possible intellect because it is capable of accepting such universalised species' (S.T., I, q. 79, art. 4). These words show clearly that for St. Thomas the acting intellect is the power by which the soul applies ens to sensations, and hence is proper to the soul in so far as it feels both its sensations and the completely universal idea of being.

We can now reach some conclusions about the nature of the acting and possible intellects. The soul possesses an innate light which is the idea of being in all its universality. This idea can be considered in two relationships. First, the soul uses and applies it in order to universalise sensations. In this respect, it forms the acting intellect. Second, the intelligent spirit beholds it continually as the idea transforms itself in all other ideas (all possible ideas are only the idea of being furnished with various determinations). This capacity for auto-transformation enables the idea to form the possible intellect. These considerations explain clearly the truth of the Aristotelian distinction between the two intellects: 'The soul possesses an intellect that becomes all things (the possible intellect), and an intellect that makes all things (the acting intellect)': Est quidam intellectus talis qui omnia fiat, et quidam qui omnia faciat (De Anima, bk. 3, lect. 10). As I said, the idea of being becomes all ideas: this is the possible intellect; and through the idea of being the soul forms all ideas: this is the acting intellect.