Thomas Aquinas - Summa Theologica, Part I (Prima Pars)

Obj. 2: Further, whatever is best must be attributed to God. But with us that which is composite is better than that which is simple; thus, chemical compounds are better than simple elements, and animals than the parts that compose them. Therefore it cannot be said that God is altogether simple.

On the contrary, Augustine says (De Trin. iv, 6,7): "God is truly and absolutely simple."

I answer that, The absolute simplicity of God may be shown in many ways. First, from the previous articles of this question. For there is neither composition of quantitative parts in God, since He is not a body; nor composition of matter and form; nor does His nature differ from His suppositum ; nor His essence from His existence; neither is there in Him composition of genus and difference, nor of subject and accident. Therefore, it is clear that God is nowise composite, but is altogether simple. Secondly, because every composite is posterior to its component parts, and is dependent on them; but God is the first being, as shown above (Q. 2, A. 3). Thirdly, because every composite has a cause, for things in themselves different cannot unite unless something causes them to unite. But God is uncaused, as shown above (Q. 2, A. 3), since He is the first efficient cause. Fourthly, because in every composite there must be potentiality and actuality; but this does not apply to God; for either one of the parts actuates another, or at least all the parts are potential to the whole. Fifthly, because nothing composite can be predicated of any single one of its parts. And this is evident in a whole made up of dissimilar parts; for no part of a man is a man, nor any of the parts of the foot, a foot. But in wholes made up of similar parts, although something which is predicated of the whole may be predicated of a part (as a part of the air is air, and a part of water, water), nevertheless certain things are predicable of the whole which cannot be predicated of any of the parts; for instance, if the whole volume of water is two cubits, no part of it can be two cubits. Thus in every composite there is something which is not it itself. But, even if this could be said of whatever has a form, viz. that it has something which is not it itself, as in a white object there is something which does not belong to the essence of white; nevertheless in the form itself, there is nothing besides itself. And so, since God is absolute form, or rather absolute being, He can be in no way composite. Hilary implies this argument, when he says (De Trin. vii): "God, Who is strength, is not made up of things that are weak; nor is He Who is light, composed of things that are dim."

Reply Obj. 1: Whatever is from God imitates Him, as caused things imitate the first cause. But it is of the essence of a thing to be in some sort composite; because at least its existence differs from its essence, as will be shown hereafter, (Q. 4, A. 3).

Reply Obj. 2: With us composite things are better than simple things, because the perfections of created goodness cannot be found in one simple thing, but in many things. But the perfection of divine goodness is found in one simple thing (QQ. 4, A. 1, and 6, A. 2). _______________________

EIGHTH ARTICLE [I, Q. 3, Art. 8]

Whether God Enters into the Composition of Other Things?

Objection 1: It seems that God enters into the composition of other things, for Dionysius says (Coel. Hier. iv): "The being of all things is that which is above being—the Godhead." But the being of all things enters into the composition of everything. Therefore God enters into the composition of other things.

Obj. 2: Further, God is a form; for Augustine says (De Verb. Dom. [Serm. xxxviii]) that, "the word of God, which is God, is an uncreated form." But a form is part of a compound. Therefore God is part of some compound.

Obj. 3: Further, whatever things exist, in no way differing from each other, are the same. But God and primary matter exist, and in no way differ from each other. Therefore they are absolutely the same. But primary matter enters into the composition things. Therefore also does God. Proof of the minor—whatever things differ, they differ by some differences, and therefore must be composite. But God and primary matter are altogether simple. Therefore they nowise differ from each other.

On the contrary, Dionysius says (Div. Nom. ii): "There can be no touching Him," i.e. God, "nor any other union with Him by mingling part with part."

Further, the first cause rules all things without commingling with them, as the Philosopher says (De Causis).

I answer that, On this point there have been three errors. Some have affirmed that God is the world-soul, as is clear from Augustine (De Civ. Dei vii, 6). This is practically the same as the opinion of those who assert that God is the soul of the highest heaven. Again, others have said that God is the formal principle of all things; and this was the theory of the Almaricians. The third error is that of David of Dinant, who most absurdly taught that God was primary matter. Now all these contain manifest untruth; since it is not possible for God to enter into the composition of anything, either as a formal or a material principle. First, because God is the first efficient cause. Now the efficient cause is not identical numerically with the form of the thing caused, but only specifically: for man begets man. But primary matter can be neither numerically nor specifically identical with an efficient cause; for the former is merely potential, while the latter is actual. Secondly, because, since God is the first efficient cause, to act belongs to Him primarily and essentially. But that which enters into composition with anything does not act primarily and essentially, but rather the composite so acts; for the hand does not act, but the man by his hand; and, fire warms by its heat. Hence God cannot be part of a compound. Thirdly, because no part of a compound can be absolutely primal among beings—not even matter, nor form, though they are the primal parts of every compound. For matter is merely potential; and potentiality is absolutely posterior to actuality, as is clear from the foregoing (Q. 3, A. 1): while a form which is part of a compound is a participated form; and as that which participates is posterior to that which is essential, so likewise is that which is participated; as fire in ignited objects is posterior to fire that is essentially such. Now it has been proved that God is absolutely primal being (Q. 2, A. 3).

Reply Obj. 1: The Godhead is called the being of all things, as their efficient and exemplar cause, but not as being their essence.

Reply Obj. 2: The Word is an exemplar form; but not a form that is part of a compound.

Reply Obj. 3: Simple things do not differ by added differences—for this is the property of compounds. Thus man and horse differ by their differences, rational and irrational; which differences, however, do not differ from each other by other differences. Hence, to be quite accurate, it is better to say that they are, not different, but diverse. Hence, according to the Philosopher (Metaph. x), "things which are diverse are absolutely distinct, but things which are different differ by something." Therefore, strictly speaking, primary matter and God do not differ, but are by their very being, diverse. Hence it does not follow they are the same.

Having considered the divine simplicity, we treat next of God's perfection. Now because everything in so far as it is perfect is called good, we shall speak first of the divine perfection; secondly of the divine goodness.

Concerning the first there are three points of inquiry:

(1) Whether God is perfect?

(2) Whether God is perfect universally, as having in Himself the perfections of all things?