Appendix 14.

(528) [St. Thomas and natural and scientific knowledge]

In some passages of St. Thomas it could seem that the matter of our knowledge is supplied only by the exterior senses without any contribution from the internal feeling of myself. But if we compare the various observations he makes on the subject, his mind appears very clear: the matter of our knowledge comes from two sources, external sensations and the internal feeling of the soul itself.

St. Augustine had said: 'The mind knows itself through itself because it is incorporeal' (De Trin., bk. 9, c. 3). Clearly he teaches that the soul has a feeling, or rather is itself a substantial feeling, and therefore supplies the understanding with some matter of knowledge that cannot in any way be furnished by the bodily senses. Aristotle, whom the Scholastics had adopted as their guiding star (where he was not opposed to the Christian faith), took another view. According to him, 'The intellect understands nothing without corporeal phantasm' (De Anima, bk. 3, c. 30). St. Thomas' acute mind saw that Augustine's teaching was true from one point of view, and Aristotle's from another, and he tried to reconcile the two.

First, he established that no species offering a likeness of the soul could be drawn from phantasms; no idea of our soul, which is completely different from corporeal nature, could therefore be gained from corporeal phantasms: anima non cognoscitur per speciem a sensibus abstractam, quasi intelligatur species illa esse animae similitudo (De Veri, q. 10, art. 8). Secondly, he thought the best way of discovering how we know the nature of the soul was to examine the approach used by philosophers in their discussion about its properties. He observed that in meditating on the nature of the soul, they first examined its acts, especially its ideas. He says:

St. Thomas concludes that the abstract species (ideas) of material things were necessary to the philosophers' knowledge of the soul's nature not because the species could supply a likeness of the soul, sed quia naturam speciei considerando, quae a sensibilibus abstrahitur, invenitur natura animae, in qua huiusmodi species recipitur [but because, by considering the nature of the species abstracted from sensible things, we discover the nature of the soul in which this species is received] (ibid.). Thus it was not the sensible phantasms, but the species formed in us by the acting intellect, as we have seen, that provided information about the soul. This species, of a completely different nature from phantasms, supplies a starting point for discovering the nature of the soul.
This was scientific knowledge of the soul, reducible to a definition. But there is also a natural knowledge of the soul. Each of us is conscious of having, or rather being, an incommunicable, personal feeling, and of perceiving the feeling expressed in the word myself. We know that this feeling is not found in any way in the corporeal qualities of extension, and so on. These are all extrasubjective; myself is the subject itself.

This kind of knowledge did not, it seems to me, escape the attention of St. Thomas. To understand his mind, we must keep before us the expressions he uses to indicate the two kinds of knowledge I am discussing, scientific and popular. The former is founded on argued reasoning; the latter consists in immediate perception.

St. Thomas, therefore, declares that we cannot say we know the nature of anything if its specific or generic difference is unknown; only by means of this difference can we form a proposition containing the definition of the thing (cum res speciali aut generali cognitione definitur). Only scientific knowledge enables us to know the nature of the soul. But in speaking of what I would call popular or natural knowledge, St. Thomas calls it 'that by which the soul knows itself individually' (that is, quantum ad id quod est ei proprium [relative to what is proper to itself]). This kind of knowledge corresponds exactly to what I call perception of our soul, which takes place for the first time when we say to ourselves: I AM. It is composed of the feeling of myself (matter) and of the idea of being in all its universality (form) and nothing more. We do not know expressly any differences it may have with other things, nor do we compare it with other objects. This kind of knowledge, according to St. Thomas, is such that it makes known only the existence of the soul, not its essence (per hanc cognitionem cognoscitur an est anima; - per aliam vero - scitur quid est anima).

Before proceeding, I would like to make an observation about calling perception 'knowledge by which we know the soul exists.' Aquinas himself puts the following objection: 'We cannot know that something exists unless we first know what it is' (De Verit., q. 10, art. 12), and answers it: 'In order to know that something exists, it is not necessary to know what it is by definition (that is, to know it scientifically), but what is meant by its name.' Here St. Thomas is describing popular knowledge expressed by the way people name things. In our case, this knowledge is reduced to a global perception of the thing, without either comparison with other things or the realisation of the differences necessary for forming a perfect definition of it. I point this out to allow the reader to reflect that St. Thomas' knowledge 'by which something is known to be' (qua scitur aliquid esse) does not express the pure existence of the thing. We could not know the thing without sufficient information to distinguish it from all other things with which it shares existence.

We are now in a position to note the harmony between St. Thomas' teaching on knowledge qua cognoscitur an est anima [by which the soul is known to exist] and mine on perceptive or natural and popular knowledge.

Following the teaching of St. Augustine, St. Thomas affirms that 'the essence of the soul is always present to our intellect' (ipsa ejus essentia intellectui nostro est praesens). To perceive this essence, our understanding needs only to posit the act by which it perceives the essence of the soul. He concludes: anima per essentiam suam se videt, id est, hoc ex ipso quod essentia sua est sibi praesens, est potens exire in actum cognitionis sui ipsius [the soul sees itself through its essence, that is, it has the ability to arrive at knowledge of itself because its essence is present to itself] (De Verit., 10, 8). He likens this knowledge to knowledge in our memory saying that sicut aliquis ex hoc quod habet alicujus scientiae habitum, ex ipsa praesentia habitus est potens percipere illa quae subsunt illi habitui [someone who has a habit of knowledge, can perceive the things subject to the habit] (ibid.). And this direct knowledge that the soul has of itself without phantasms, he calls habitual.

For the understanding to come to actual knowledge of the soul (St. Thomas continues), a sufficient reason must be provided by the acts of the soul itself. 'Therefore I say that, as regards the actual knowledge by which anyone considers his soul in act, the soul is known only by its acts. A person perceives that he has a soul, that he lives and exists because he realises that he feels, knows, and performs other vital operations' (ibid.). No one can doubt this.

Let me conclude with an observation. Forget for a moment reflective knowledge of ourselves and remember we are speaking only of direct, immediate knowledge, the perception of OURSELVES; our soul is only our own feeling of this OURSELVES. Now it is clear that we can perceive ourselves intellectively only by our acts. But some acts are essential, like feeling and the act of the acting intellect (with which we perceive being) - both St. Thomas and Aristotle accept this last act. Because such acts are essential, we can never lack them. We could, therefore, have actual perception of ourselves even in the first moments of our existence if there were some stimulus to draw our attention to ourselves. But as long as such a stimulus is missing, we are left only with the power to acquire this knowledge: est potens [anima] exire in actum cognitionis sui ipsius [the soul has the capacity to produce an act of knowledge of itself].