Chapter 084 - How the Soul United to the Body Understands Corporeal Things Which Are Below Itself

We must reject the opinion of the ancients, who held truth to be unattainable about corporeal things which are in a state of continual change; also that of Plato, who admitted another genus of beings separate from matter and motion, viz. ideas, by means of which the soul was supposed to participate in sensible things, as though the intellect were to be referred to these, which would be immaterial and separate. This has been shown to be false, because it would exclude the cognizance of matter and motion, which form part of knowledge. It has been seen, moreover, to be absurd to seek the knowledge of things which are manifest to us, through others which cannot be their substance, inasmuch as they have a different mode of being; therefore we must conclude that knowledge is according to the mode of the faculties of the being who knows.

Thus as whiteness exists in different modes on a wall and in the eye, so the species of bodies exist in the intellect according to the nature and mode of the intellect, viz, immaterially and intelligibly; - for everything is received according to the capacity of the recipient; the intellect, therefore, knows bodies certainly and universally.

The ancient philosophers, who held things known to be material and corporeal and to have a common nature with the soul, supposed them to exist in the soul in such manner as to be known directly by its essence; but this opinion is to be rejected, because it would require things known to be within the soul's nature, and to be forms of individual effects; for a thing is only known in so far as it is actual, not as it is in potentia. Moreover, if it were necessary for the thing known to be materially in the knower, why should things which subsist materially outside the soul be devoid of understanding? If the soul knows fire by means of fire, the fire which exists outside the soul should also know fire; which cannot be admitted. It remains, therefore, that material things, as known, exist in the knower immaterially; and the more immaterially an intelligence possesses the forms of things known, so much the more perfectly it knows them.

The soul cannot know by means of species naturally infused; for it is sometimes in potentia both according to sense and to intelligence, being actualized as regards sense by sensible acts, and as regards intelligence by training and experience. Neither does the soul forget everything by union with the body; for a natural operation is not entirely hindered by that which properly belongs to nature, as does the union of the soul with the body; nor is that forgotten which is naturally known.

The conception of sensible things requires that their forms should not subsist without matter; therefore Avicenna held that intelligible species flowed from the Ultimate Intelligence into our intellect, which thus became actualized and received intelligible forms. But this theory assigns no sufficient reason for the union of the soul with the body, for such union is not for the sake of the body, but for that of the soul; and if the intelligible species were received by the influence of some separate principle, not through the senses, the soul's union with the body would be useless. Nor can the senses be only an exciting cause; for if it were natural to the soul to understand by means of species flowing from the acting intellect, the result would be that, through natural tendency, the soul would turn to the intellect for the reception of sensible species when the corresponding sense was wanting: thus the blind might have a knowledge of colour: which is evidently false. Hence we conclude that the intelligible species by which the soul understands do not flow from separate forms.

It may, however, be said that the soul knows things in their eternal conception, if by that we mean causally, inasmuch as the natural light by which we know is a certain participation in the Divine light; but not in their eternal conception alone, for in this present state we require intelligible species taken from material things besides the Divine light; thus it is written: "The light of Thy countenance is signed upon us, O Lord." With regard to objective knowledge, the soul does not in her present state know things in their eternal conception. This belongs to the beatified soul which sees everything in God.

Neither is intellectual knowledge taken from sensible things according to the mode of defluxions in sense, as held by Democritus, who did not admit the difference between sense and intellect; but the active intellect renders the images received from the senses intelligible by means of certain abstractions. Inasmuch, therefore, as these images are not sufficient to act upon the possible intellect, but require to be made intelligible by means of the active intellect, sensible knowledge cannot be assigned as the whole or perfect cause of intellectual knowledge; it is rather the matter of the cause, than the cause itself.

The intellect, indeed, conjoined to a passible body, cannot understand without turning to phantasms, and since it does not itself make use of bodily organs, unless its action required the help of some other faculty which does make use of such organs, it would be in no way hindered by their injury; the contrary of which we find to be the case, since through physical injuries, memory and imagination not only lose knowledge already acquired, but are prevented from acquiring new knowledge. Moreover, whoever tries to understand anything will experience that he forms for himself images or phantasms in which he seems to look at what he is endeavouring to understand, the reason being that the knowing faculty is proportioned to the things which are to be known.

Thus the judgment of the intellect is hindered when the senses are impaired; for when the object and end of the judgment is unknown the judgment itself cannot act; as we find to be the case when through the imperfection of a sense that particular which is the term of the judgment is not perceived. For the object of our intellect being sensible nature, it is impossible that the judgment of the intellect should be perfect when the senses are imperfect by which sensible things are known.