As man is bound up with “the spiritual world,” “the intellectual world” above him, in which Thomas sees the “immaterial intellectual beings,” so he raises himself from below out of the “world of the natural kingdoms,” in which human power of thought can find “those things which the spiritual world has implanted in the natural world” [p. 67].
This “implanting” occurs according to the Aristotelian-Thomistic conception not as a filling, as it might be, of some ready-waiting vessels, but as creative action.
Original matter Thomas does not think of as a vessel — not even as in the least useful for anything — but as “maxime imperfectum” — as, if one can so put it — perfect imperfection, as “maxime in potential” i.e., only in the condition of greatest potentiality. Every smallest degree of reality, of “actus of” forma must be imparted first from outside, from the spiritual world, and every “being real,” every “actus,” must ultimately originate in the “actus purus” the perfect reality, God. Between the poles of “original matter,” the absolute bare “potentiality,” and God, the “actus purus,” lies the whole material and spiritual world; the one at the potential, the other at the actual pole, but in such a way that the light of the “actus” reaches to the nethermost, and the shadow of the “potentia” reaches to the topmost.
As an example of the struggle of Scholastic thought concerning the knowledge of “what has been imparted to the natural Kingdoms from the spiritual world,” let us translate a few passages from the Quaestio of Thomas “Concerning Spiritual Creatures.”
... The more perfect a form is, the more it prevails over the bodily matter, which can be seen by considering the various degrees of forms. The form of the Elements (earth, water, air or fire) has no other activity than what is derived from the active and passive qualities which are the conditions of bodily material. The form of mineral body has a certain activity which exceeds the active and passive qualities, and which is connected with this special form through the influence of a heavenly body: as when the magnet attracts the iron, and the sapphire heals abscesses. Beyond that, however, the vegetable soul has an activity, which subserves in fact the active and passive organic qualities; and over and above the range of these qualities, it develops still another function, peculiar to it, by causing nourishment and growth up to its set objective, and other similar things. The sensitive soul has furthermore an activity up to which the active and passive qualities in us may reach; what happens is that they are employed in compounding an organ through which such an activity is performed, such as seeing, hearing, desire, and so on. But the most perfect of the forms, namely, the human soul, which is the goal of all natural forms, has an activity which completely surpasses matter, and which functions through no bodily organ, namely, the power of intelligence. And since the existence of anything corresponds to its activity, the existence of the human soul must necessarily far surpass bodily matter, and cannot be quite contained by it, even if they are in some manner in contact with each other. Now in so far as the human soul exceeds the existence of the material body, and is in a position of independence of material support, it is a spiritual substance; but in so far as it is in contact with matter, and communicates to it its own “esse,” it is a body-form it is touched by bodily matter for the reason that the highest of the lower Order is always in contact with the lowest of the higher Order, as Dionysius makes clear in Chapter VII, Concerning the Divine Names. Thus the human soul, the lowest in the Orders of spiritual substances, can communicate its “being” to the human body, — which is also the worthiest, to the end that soul and body become one, as do form and matter.
According to Aristotelian doctrine, however, which Thomas never tires of defending against the Platonists, man is not something composed of these variously graduated forms. But the “most noble form” among all forms that have a material background, the “anima humana” has also the most exquisite “operatio,” with a power that includes all other functions.
It is shown in the active and operative powers, that the higher a power is, the more accomplishments it has, and this not in a composite way, but as separate unities; wherefore the more perfect form effects everything through a unity which lower forms do through a plurality. If, for instance, the form of the soulless body provides the “being” and the “being body,” and the vegetable form provides not only this but in addition life, and the anima sensitiva all this and in addition the power of reacting to feelings, the rational soul provides all this also, and over and above it the quality of being rational. ... In the embryo the less perfect form disappears when the more perfect one appears. And if in the embryo there is at first only the vegetable soul, this soul is removed, when the embryo has attained greater perfection, as being the less perfect form, and the more perfect follows, which is at the same time the vegetable and “receptive” soul; and when this goes, there follows the last and most perfect, namely, the “rational soul” ...
Originally, in Adam and Eve, the “anima rationalis” or “humana” was, according to Thomistic doctrine, blessed with “original justice,” which gave it the power to keep the material body intact against the laws of matter, free from sickness and death. Since the Fall the body has been exposed to the material processes of “generatio” and “corruptio” — of becoming and disintegrating. But since every movement on earth — including that of growth and disintegration — is caused by the “heavenly bodies,” man has been exposed in his body since then not only to the progressive movement impulses, which are thought, as impulses of growth, to proceed from the sun, but also to all destruction-impulses, which proceed from the retrograde movements of Mars. And from the body the intellect and the will can be clouded through the passions.
The heavenly body has according to Aristotle and Thomas a quite immaterial existence; although it is present in the kingdom of matter as pure movement. It is material, not in the sense of “being” material, but in the sense of position. All its powers, specially that of light, are super-material, but moving and causing motion in matter. It is itself therefore indestructible, but the movements to which it gives rise in the Kingdom of matter can cause destruction.
In the Commentary on Aristotle's writing Concerning Heaven and the World, Thomas writes:
The heavenly bodies are active, but not passive; therefore they touch, but are not touched. Therefore also the tangible bodily qualities are not present in the heavenly bodies, as they are in the lower bodies, but in a more conspicuous manner, namely, in the active cause: for there is no cold or warm, wet or dry, but the power which produces such results.
For this reason the heavenly bodies can penetrate each other and all material substances. For they are not conceived as being “in heaven,” but — in the sense of the Ptolemaic System — as interpenetrating spheres, which all have the Earth as a common central point, and are so different in their individual movements that each of the seven Planet spheres preserves its own speed and its own forward and backward motion.
The eighth sphere, that of the fixed stars, revolves most worthily, the ninth and tenth, those of the Chrystal and shining heaven are, like God — the Prime unmoved Mover — motionless. In the lap of these all-embracing Spheres, spins the world.
The relationship of the heavenly bodies to the separate stars is such that
... the Stars have no movement of their own, but are carried with the movements of the spheres, in which they are implanted; not as if they were of a different nature, such as an iron nail embedded in a wooden wheel, but behaving as an entity of the same nature, in such way that the star is a nobler part of the sphere itself, in which the light and the operative power are united. ... All are round the central point, the Earth. ...
These spheres are packed with the immaterial intellectual Beings, and serve them, with their “virtutes” — principally with light — as instruments for their work on Earth.
But man ranges over the realm of matter in which the heavenly bodies carry out their works, with his “anima humana,” which is not only the highest body form, but also the lowest spiritual being, and ascends into the spiritual world above [vide infra, p 135 et seq].
Human knowledge is at the same time the highest activity of which an earthbound substance is capable, and also the lowest kind of intellectual activity, compared with the vision that belongs to the Hierarchies. From this standpoint of the “anima humana” follows with iron logic, carried into the most exact details, the construction of the Thomistic doctrine of knowledge.