In the fifth sententia of the first chapter of Book 1, Isidore gives a summary statement of an idea familiar in Western divinity: that the divine attributes are identical with the divine essence (as one example from recent history, cf. Bavinck here). As John of Damascus says, “[O]ne may not speak of quality in connection with God, from fear of implying that He was a compound of essence and quality” (Exposition of the Orthodox Faith 1.13). This doctrine, then, is intimately bound up with the doctrine of divine simplicity (the subject to which Isidore will next turn).
As Isidore puts it:1
Non usu nostro aliud Deum putari, aliud pulchritudinem eius, atque aliud magnitudinem ipsius, sicut aliud est homo, aliud pulchritudo, quia, desistente pulchritudine, homo manet. Ac per hoc, qui ita intellegit Deum, corporeum esse credit, dum pulchritudo et magnitudo Dei ipse Deus sit.
Not, as is the case with us, ought God to be thought of as one thing, his beauty another, his greatness still another, just as man is one thing, [his] beauty another, since, when his beauty ceases, the man remains. And, on account of this, he who understands God in such a way [i.e., in the same way as he understands man] believes him to be corporeal, since [in reality] the beauty and the greatness of God is God himself.
The distinction between creator and creature is again to the fore. Man’s essence or nature is not the same as the various attributes he possesses. But, Isidore says, to think in this way of God is to think “corporeally.” That is, it is to think of the divine nature as changeable: just as, through the flux of human life, a man remains who he is, such that, even if beauty departs from a man, he is still a man–homo manet. But we have already seen that mutability compromises divine perfection. That these are the terms in which he is thinking one might guess from the fact that Augustine had previously done so (On the Trinity 6.6-7):2
But if it is asked how that substance is both simple and manifold: consider, first, why the creature is manifold, but in no way really simple. And first, all that is body is composed certainly of parts; so that therein one part is greater, another less, and the whole is greater than any part whatever or how great soever. For the heaven and the earth are parts of the whole bulk of the world; and the earth alone, and the heaven alone, is composed of innumerable parts; and its third part is less than the remainder, and the half of it is less than the whole; and the whole body of the world, which is usually called by its two parts, viz. the heaven and the earth, is certainly greater than the heaven alone or the earth alone. And in each several body, size is one thing, color another, shape another; for the same color and the same shape may remain with diminished size; and the same shape and the same size may remain with the color changed; and the same shape not remaining, yet the thing may be just as great, and of the same color. And whatever other things are predicated together of body can be changed either all together, or the larger part of them without the rest. And hence the nature of body is conclusively proved to be manifold, and in no respect simple. The spiritual creature also, that is, the soul, is indeed the more simple of the two if compared with the body; but if we omit the comparison with the body, it is manifold, and itself also not simple. For it is on this account more simple than the body, because it is not diffused in bulk through extension of place, but in each body, it is both whole in the whole, and whole in each several part of it; and, therefore, when anything takes place in any small particle whatever of the body, such as the soul can feel, although it does not take place in the whole body, yet the whole soul feels it, since the whole soul is not unconscious of it. But, nevertheless, since in the soul also it is one thing to be skillful, another to be indolent, another to be intelligent, another to be of retentive memory; since cupidity is one thing, fearanother, joy another, sadness another; and since things innumerable, and in innumerable ways, are to be found in the nature of the soul, some without others, and some more, some less; it is manifest that its nature is not simple, but manifold. For nothing simple is changeable, but every creature is changeable.
But God is truly called in manifold ways, great, good, wise, blessed, true, and whatsoever other thing seems to be said of Him not unworthily: but His greatness is the same as His wisdom; for He is not great by bulk, but by power; and His goodness is the same as His wisdom and greatness, and His truth the same as all those things; and in Him it is not one thing to be blessed, and another to be great, or wise, or true, or good, or in a word to be Himself.
A God who was less than maximally perfect would not be an absolute reality and an appropriate object of worship. A God who was less than ultimate and absolute would be an idol. Now an absolute reality must be a se, from itself, and so not dependent on anything distinct from itself for either its nature or its existence. If God had properties in the way creatures have them, however, he would be distinct from them and so dependent on them. This is the case whether one thinks of a property of x as a constituent of x, or as an entity external to x to which x is tied by the asymmetrical relation (or nonrelational tie) of instantiation. If the properties of x are constituents or ontological (proper) parts of x, then x will depend on them in the same way that any whole composed of parts depends on its parts. But if x is tied to its properties by the asymmetrical relation of instantiation, it is still the case that x will depend on them: if x is F in virtue of x‘s instantiation of F-ness, then F-ness is a logically prior condition of x‘s being F. In sum, the divine aseity would seem to require that God be rather than have his attributes.