SUMMA THEOLOGICA. Thomas Aquinas
confusion devoid of all distinction; except Anaxagoras, who taught that the intellect alone was distinct and without admixture. But previous to the work of distinction Holy Scripture enumerates several kinds of differentiation, the first being that of the heaven from the earth, in which even a material distinction is expressed, as will be shown later ( Article [3]; Question [68], Article [1]). This is signified by the words, "In the beginning God created heaven and earth." The second distinction mentioned is that of the elements according to their forms, since both earth and water are named. That air and fire are not mentioned by name is due to the fact that the corporeal nature of these would not be so evident as that of earth and water, to the ignorant people to whom Moses spoke. Plato (Timaeus xxvi), nevertheless, understood air to be signified by the words, "Spirit of God," since spirit is another name for air, and considered that by the word heaven is meant fire, for he held heaven to be composed of fire, as Augustine relates (De Civ. Dei viii, 11). But Rabbi Moses (Perplex. ii), though otherwise agreeing with Plato, says that fire is signified by the word darkness, since, said he, fire does not shine in its own sphere. However, it seems more reasonable to hold to what we stated above; because by the words "Spirit of God" Scripture usually means the Holy Ghost, Who is said to "move over the waters," not, indeed, in bodily shape, but as the craftsman's will may be said to move over the material to which he intends to give a form. The third distinction is that of place; since the earth is said to be under the waters that rendered it invisible, whilst the air, the subject of darkness, is described as being above the waters, in the words: "Darkness was upon the face of the deep." The remaining distinctions will appear from what follows ( Question [71]).
Whether the formless matter of all corporeal things is the same?
Objection 1: It would seem that the formless matter of all corporeal things is the same. For Augustine says (Confess. xii, 12): "I find two things Thou hast made, one formed, the other formless," and he says that the latter was the earth invisible and shapeless, whereby, he says, the matter of all corporeal things is designated. Therefore the matter of all corporeal things is the same.
Objection 2: Further, the Philosopher says (Metaph. v, text. 10): "Things that are one in genus are one in matter." But all corporeal things are in the same genus of body. Therefore the matter of all bodies is the same.
Objection 3: Further, different acts befit different potentialities, and the same act befits the same potentiality. But all bodies have the same form, corporeity. Therefore all bodies have the same matter.
Objection 4: Further, matter, considered in itself, is only in potentiality. But distinction is due to form. Therefore matter considered in itself is the same in all corporeal things.
On the contrary, Things of which the matter is the same are mutually interchangeable and mutually active or passive, as is said (De Gener. i, text. 50). But heavenly and earthly bodies do not act upon each other mutually. Therefore their matter is not the same.
I answer that, On this question the opinions of philosophers have differed. Plato and all who preceded Aristotle held that all bodies are of the nature of the four elements. Hence because the four elements have one common matter, as their mutual generation and corruption prove, it followed that the matter of all bodies is the same. But the fact of the incorruptibility of some bodies was ascribed by Plato, not to the condition of matter, but to the will of the artificer, God, Whom he represents as saying to the heavenly bodies: "By your own nature you are subject to dissolution, but by My will you are indissoluble, for My will is more powerful than the link that binds you together." But this theory Aristotle (De Caelo i, text. 5) disproves by the natural movements of bodies. For since, he says, the heavenly bodies have a natural movement, different from that of the elements, it follows that they have a different nature from them. For movement in a circle, which is proper to the heavenly bodies, is not by contraries, whereas the movements of the elements are mutually opposite, one tending upwards, another downwards: so, therefore, the heavenly body is without contrariety, whereas the elemental bodies have contrariety in their nature. And as generation and corruption are from contraries, it follows that, whereas the elements are corruptible, the heavenly bodies are incorruptible. But in spite of this difference of natural corruption and incorruption, Avicebron taught unity of matter in all bodies, arguing from their unity of form. And, indeed, if corporeity were one form in itself, on which the other forms that distinguish bodies from each other supervene, this argument would necessarily be true; for this form of corporeity would inhere in matter immutably and so far all bodies would be incorruptible. But corruption would then be merely accidental through the disappearance of successive forms---that is to say, it would be corruption, not pure and simple, but partial, since a being in act would subsist under the transient form. Thus the ancient natural philosophers taught that the substratum of bodies was some actual being, such as air or fire. But supposing that no form exists in corruptible bodies which remains subsisting beneath generation and corruption, it follows necessarily that the matter of corruptible and incorruptible bodies is not the same. For matter, as it is in itself, is in potentiality to form.
Considered in itself, then, it is in potentiality in respect to all those forms to which it is common, and in receiving any one form it is in act only as regards that form. Hence it remains in potentiality to all other forms. And this is the case even where some forms are more perfect than others, and contain these others virtually in themselves. For potentiality in itself is indifferent with respect to perfection and imperfection, so that under an imperfect form it is in potentiality to a perfect form, and "vice versa." Matter, therefore, whilst existing under the form of an incorruptible body, would be in potentiality to the form of a corruptible body; and as it does not actually possess the latter, it has both form and the privation of form; for want of a form in that which is in potentiality thereto is privation. But this condition implies corruptibility. It is therefore impossible that bodies by nature corruptible, and those by nature incorruptible, should possess the same matter.
Neither can we say, as Averroes [*De Substantia Orbis ii.] imagines, that a heavenly body itself is the matter of the heaven---beings in potentiality with regard to place, though not to being, and that its form is a separate substance united to it as its motive force. For it is impossible to suppose any being in act, unless in its totality it be act and form, or be something which has act or form. Setting aside, then, in thought, the separate substance stated to be endowed with motive power, if the heavenly body is not something having form---that is, something composed of a form and the subject of that form---it follows that in its totality it is form and act. But every such thing is something actually understood, which the heavenly bodies are not, being sensible. It follows, then, that the matter of the heavenly bodies, considered in itself, is in potentiality to that form alone which it actually possesses. Nor does it concern the point at issue to inquire whether this is a soul or any other thing. Hence this form perfects this matter in such a way that there remains in it no potentiality with respect to being, but only to place, as Aristotle [*De Coelo i, text. 20] says. So, then, the matter of the heavenly bodies and of the elements is not the same, except by analogy, in so far as they agree in the character of potentiality.
Reply to Objection 1: Augustine follows in this the opinion of Plato, who does not admit a fifth essence. Or we may say that formless matter is one with the unity of order, as all bodies are one in the order of corporeal creatures.
Reply to Objection 2: If genus is taken in a physical sense, corruptible and incorruptible things are not in the same genus, on account of their different modes of potentiality, as is said in Metaph. x, text. 26. Logically considered, however, there is but one genus of all bodies, since they are all included in the one notion of corporeity.
Reply to Objection 3: The form of corporeity is not one and the same in all bodies, being no other than the various forms by which bodies are distinguished, as stated above.
Reply to Objection 4: As potentiality is directed towards act,