but that only which actually is colored. And in the same manner as is manifest, the intellect, in so far as it knows material things, knows that only which is in act. … Hence, also, in immaterial substances, each one is intelligible by its essence, accordingly as it is in act by its essence. Therefore, the essence of God, which is a pure and perfect act, is absolutely and perfectly intelligible by itself; thus God knows, by his essence, not only himself but also all other things. But the essence of the angel belongs to the class of intelligible beings as an act, but not as a pure and complete act, wherefore his understanding is not completed by his essence. For, although the angel knows himself by his essence, he cannot know all things by his essence, but knows those distinct from himself only by their images. But the human intellect in the class of intelligible beings is only a possible being. … Therefore, considered in its essence, it is an intelligent power; hence of itself it has the faculty of understanding, but not of being understood, except inasmuch as it acts. On this account the Platonists placed the order of intelligible beings above the order of intellect; because the intellect understands only by participation of the intelligible; but according to them, that which participates is beneath that of which it participates. If, then, the human intellect places itself in act by the participation of separate intelligible forms, as the Platonists held, it would know itself by this participation of incorporeal things. But as it is natural to our intellect in the present life to look to material and sensible things, it follows that our intellect knows itself only as it is placed in act by the species (ideas) abstracted from sensible things by the light of the intellect acting, which is the act of the intelligible things themselves. … Therefore our intellect does not know itself by its essence but by its acts."
Such is the doctrine of St. Thomas. Cardinal Cajetan, one of the most penetrating and subtile minds that ever existed, has a commentary on this passage, worthy of the text. These are his words: "Two things expressly follow, from what is said in the text. The first is, that our intellect has of itself the faculty of understanding. The second is, that our intellect has not of itself the faculty of being understood. Hence the order of intellect is below the order of intelligible beings. For if the perfection, which our intellect has of itself, is sufficient to understand, but not to be understood, it necessarily follows that greater perfection is required in a thing to be understood than to understand. And because St. Thomas saw this consequence, which at first sight does not seem true, and might even be objected to him, he excludes this apprehension, by showing that this must be admitted to be true not only by the Peripatetics, from whose doctrine it results, but also by the Platonists."
But afterwards, in answer to an objection brought by Scotus, called the Subtle Doctor, he adds: "But because in order to understand an intellect and an intelligible object are required, and the relation of the intellect to the intelligible, is the relation of the perfectible to its perfection, since the intellect in act consists in its being itself the intelligible thing, as is evident from what has been said above; it follows that immaterial beings are divided into two orders, intellects, and things intelligible. And as the intelligible consists in perfective immateriality, it follows that any thing is intelligible inasmuch as it is immaterially perfective. That intelligibility requires immateriality is shown by this, that no material thing is intelligible, unless, inasmuch as it is abstracted from matter. … It has already been shown that any thing is intelligible by this, that not only itself, but others, also, are in the intelligible order, either in act or in potentiality; it is thus nothing more than to be perfected or perfectible by the intelligible."
123. This theory may be more or less solid, but it is in either case something more than ingenious; it raises a new problem in philosophy of the highest importance: to assign the conditions of intelligibility. It has moreover the advantage of being in accordance with a fact attested by experience; this fact is the difficulty experienced by the mind in knowing itself. If it is immediately intelligible, why does it not know itself? What condition is wanting? Its intimate presence? It has not only presence but identity. Perhaps the effort to know itself? But the greater part of philosophy has no other end than this knowledge. By denying immediate intelligibility to the soul, we can explain why so great a difficulty is involved in ideological and psychological investigations, by showing the reason of the obscurity experienced in passing from direct to reflex acts.
124. The opinion of St. Thomas is not a mere conjecture: we may, in order to establish it in some manner upon fact, assign a reason which seems to us greatly to strengthen it, and which may be regarded as merely an extension of the one already given.
A thing to be intelligible must have two qualities: immateriality, and the activity necessary to operate upon the intelligent being. This activity is indispensable, for in the act of intelligence, the intellect is in some sense passive. When the idea is present, the intellect cannot but know it: when it is wanting, it is impossible for the intellect to know it. The idea, therefore, enables the intellect to act; without it the intellect can do nothing. Consequently, if we admit that any being can serve as idea to the intellect, we must concede that being an activity to excite intellectual action; and so far we make it superior to the intellect excited.
Thus we explain why our intellect, in this life at least, does not know itself by itself. Experience shows that its activity needs to be excited. Left to itself it is like one asleep; and this want of activity in our mind, in the absence of exciting influences, is one of the most constant of psychological facts.
This is not, however, to say that we have no spontaneity, and that no action is possible without an external determining cause; but only that this same spontaneous development would not exist, if we had not previously been subjected to the influence of causes which brought out our activity. We may learn things not taught us; but we could learn nothing, if teaching had not presided over the first development of our mind. There are, it is true, many ideas in our mind, which are not sensations, and which cannot have emanated from them; but it is equally true that a man, deprived of all his senses, could not think, because his mind would want the exciting cause.
125. We have dwelt thus long upon the explanation of the problem of intelligibility, because we consider it of scarcely less importance than that of intelligence, although we do not find it treated in philosophical works as it merits. We will now reduce this doctrine to clear and simple propositions, so that the reader may form a more complete conception of it; and also, in order to deduce some consequences which have been only slightly indicated in our exposition:
I. A thing must be immaterial in order to be immediately intelligible.
II. Matter cannot be intelligible by itself.
III. The relations of spirits to bodies, or the representation of the latter in the former, cannot be purely objective.
IV. Some other class of relations must necessarily be admitted to explain the representative union of the world of intelligences with the corporeal world.
V. Immediate objective representation supposes activity in the object.
VI. The power of an object to represent itself to the eyes of an intelligence, supposes in it a faculty of acting on that intelligence.
VII. This faculty necessarily produces an effect, and consequently involves a kind of superiority of the object over the intelligence.
VIII. An intelligent being is not necessarily immediately intelligible.
IX. Immediate intelligibility seems to require greater perfection than intelligence.
X. Although not every intelligent being is intelligible, yet every intelligible being is intelligent.
XI. God, who is in every sense infinite activity, is infinitely intelligent and infinitely intelligible by himself.
XII. God is intelligible by all created intellects, provided it be his will to present himself immediately to them, and strengthen and elevate them as may be necessary.
XIII.
