Summa Theologica, Part I (Prima Pars) From the Complete...

Now we consider the distinction of corporeal and spiritual creatures: firstly, the purely spiritual creature which in Holy Scripture is called angel; secondly, the creature wholly corporeal; thirdly, the composite creature, corporeal and spiritual, which is man.

Objection 1: It would seem that an angel is not entirely incorporeal. For what is incorporeal only as regards ourselves, and not in relation to God, is not absolutely incorporeal. But Damascene says (De Fide Orth. ii) that "an angel is said to be incorporeal and immaterial as regards us; but compared to God it is corporeal and material. Therefore he is not simply incorporeal."

Obj. 3: Further, Ambrose says (De Spir. Sanct. i, 7): "Every creature is limited within its own nature." But to be limited belongs to bodies. Therefore, every creature is corporeal. Now angels are God's creatures, as appears from Ps. 148:2: "Praise ye" the Lord, "all His angels"; and, farther on (verse 4), "For He spoke, and they were made; He commanded, and they were created." Therefore angels are corporeal.

I answer that, There must be some incorporeal creatures. For what is principally intended by God in creatures is good, and this consists in assimilation to God Himself. And the perfect assimilation of an effect to a cause is accomplished when the effect imitates the cause according to that whereby the cause produces the effect; as heat makes heat. Now, God produces the creature by His intellect and will (Q. 14, A. 8; Q. 19, A. 4). Hence the perfection of the universe requires that there should be intellectual creatures. Now intelligence cannot be the action of a body, nor of any corporeal faculty; for every body is limited to "here" and "now." Hence the perfection of the universe requires the existence of an incorporeal creature.

The ancients, however, not properly realizing the force of intelligence, and failing to make a proper distinction between sense and intellect, thought that nothing existed in the world but what could be apprehended by sense and imagination. And because bodies alone fall under imagination, they supposed that no being existed except bodies, as the Philosopher observes (Phys. iv, text 52,57). Thence came the error of the Sadducees, who said there was no spirit (Acts 23:8).

Reply Obj. 1: Incorporeal substances rank between God and corporeal creatures. Now the medium compared to one extreme appears to be the other extreme, as what is tepid compared to heat seems to be cold; and thus it is said that angels, compared to God, are material and corporeal, not, however, as if anything corporeal existed in them.

Reply Obj. 2: Movement is there taken in the sense in which it is applied to intelligence and will. Therefore an angel is called an ever mobile substance, because he is ever actually intelligent, and not as if he were sometimes actually and sometimes potentially, as we are. Hence it is clear that the objection rests on an equivocation.

Reply Obj. 3: To be circumscribed by local limits belongs to bodies only; whereas to be circumscribed by essential limits belongs to all creatures, both corporeal and spiritual. Hence Ambrose says (De Spir. Sanct. i, 7) that "although some things are not contained in corporeal place, still they are none the less circumscribed by their substance." _______________________

Objection 1: It would seem that an angel is composed of matter and form. For everything which is contained under any genus is composed of the genus, and of the difference which added to the genus makes the species. But the genus comes from the matter, and the difference from the form (Metaph. xiii, text 6). Therefore everything which is in a genus is composed of matter and form. But an angel is in the genus of substance. Therefore he is composed of matter and form.

Obj. 2: Further, wherever the properties of matter exist, there is matter. Now the properties of matter are to receive and to substand; whence Boethius says (De Trin.) that "a simple form cannot be a subject": and the above properties are found in the angel. Therefore an angel is composed of matter and form.

I answer that, Some assert that the angels are composed of matter and form; which opinion Avicebron endeavored to establish in his book of the Fount of Life. For he supposes that whatever things are distinguished by the intellect are really distinct. Now as regards incorporeal substance, the intellect apprehends that which distinguishes it from corporeal substance, and that which it has in common with it. Hence he concludes that what distinguishes incorporeal from corporeal substance is a kind of form to it, and whatever is subject to this distinguishing form, as it were something common, is its matter. Therefore, he asserts the universal matter of spiritual and corporeal things is the same; so that it must be understood that the form of incorporeal substance is impressed in the matter of spiritual things, in the same way as the form of quantity is impressed in the matter of corporeal things.

But one glance is enough to show that there cannot be one matter of spiritual and of corporeal things. For it is not possible that a spiritual and a corporeal form should be received into the same part of matter, otherwise one and the same thing would be corporeal and spiritual. Hence it would follow that one part of matter receives the corporeal form, and another receives the spiritual form. Matter, however, is not divisible into parts except as regarded under quantity; and without quantity substance is indivisible, as Aristotle says (Phys. i, text 15). Therefore it would follow that the matter of spiritual things is subject to quantity; which cannot be. Therefore it is impossible that corporeal and spiritual things should have the same matter.

It is, further, impossible for an intellectual substance to have any kind of matter. For the operation belonging to anything is according to the mode of its substance. Now to understand is an altogether immaterial operation, as appears from its object, whence any act receives its species and nature. For a thing is understood according to its degree of immateriality; because forms that exist in matter are individual forms which the intellect cannot apprehend as such. Hence it must be that every individual substance is altogether immaterial.

But things distinguished by the intellect are not necessarily distinguished in reality; because the intellect does not apprehend things according to their mode, but according to its own mode. Hence material things which are below our intellect exist in our intellect in a simpler mode than they exist in themselves. Angelic substances, on the other hand, are above our intellect; and hence our intellect cannot attain to apprehend them, as they are in themselves, but by its own mode, according as it apprehends composite things; and in this way also it apprehends God (Q. 3).

Reply Obj. 1: It is difference which constitutes the species. Now everything is constituted in a species according as it is determined to some special grade of being because "the species of things are like numbers," which differ by addition and subtraction of unity, as the Philosopher says (Metaph. viii, text 10). But in material things there is one thing which determines to a special grade, and that is the form; and another thing which is determined, and this is the matter; and hence from the latter the genus is derived, and from the former the "difference." Whereas in immaterial things there is no separate determinator and thing determined; each thing by its own self holds a determinate grade in being; and therefore in them genus and "difference" are not derived from different things, but from one and the same. Nevertheless, this differs in our mode of conception; for, inasmuch as our intellect considers it as indeterminate, it derives the idea of their genus; and inasmuch as it considers it determinately, it derives the idea of their "difference."

Reply Obj. 2: This reason is given in the book on the Fount of Life, and it would be cogent, supposing that the receptive mode of the intellect and of matter were the same. But this is clearly false. For matter receives the form, that thereby it may be constituted in some species, either of air, or of fire, or of something else. But the intellect does not receive the form in the same way; otherwise the opinion of Empedocles (De Anima i, 5, text 26) would be true, to the effect that we know earth by earth, and fire by fire. But the intelligible form is in the intellect according to the very nature of a form; for as such is it so known by the intellect. Hence such a way of receiving is not that of matter, but of an immaterial substance.

Reply Obj. 3: Although there is no composition of matter and form in an angel, yet there is act and potentiality. And this can be made evident if we consider the nature of material things which contain a twofold composition. The first is that of form and matter, whereby the nature is constituted. Such a composite nature is not its own existence but existence is its act. Hence the nature itself is related to its own existence as potentiality to act. Therefore if there be no matter, and supposing that the form itself subsists without matter, there nevertheless still remains the relation of the form to its very existence, as of potentiality to act. And such a kind of composition is understood to be in the angels; and this is what some say, that an angel is composed of, "whereby he is," and "what is," or "existence," and "what is," as Boethius says. For "what is," is the form itself subsisting; and the existence itself is whereby the substance is; as the running is whereby the runner runs. But in God "existence" and "what is" are not different as was explained above (Q. 3, A. 4). Hence God alone is pure act.

Reply Obj. 4: Every creature is simply finite, inasmuch as its existence is not absolutely subsisting, but is limited to some nature to which it belongs. But there is nothing against a creature being considered relatively infinite. Material creatures are infinite on the part of matter, but finite in their form, which is limited by the matter which receives it. But immaterial created substances are finite in their being; whereas they are infinite in the sense that their forms are not received in anything else; as if we were to say, for example, that whiteness existing separate is infinite as regards the nature of whiteness, forasmuch as it is not contracted to any one subject; while its "being" is finite as determined to some one special nature.