3. Quod materiam habet, unde existat, mutabile est, quia de informi ad formam transit. Quod vero non habet materiam, immutabile est, sicut Deus utique est. Bene, ac substantialiter sunt ista in Deo, id est, incorruptio, immortalitas, incommutabilitas. Unde et merito cunctae praeponitur creaturae.
That which has matter, out of which it has its existence, is mutable, because it passes from having no form to having form. That which does not have matter, on the other hand, is immutable, just as God assuredly is. These things are really and substantially in God–that is, incorruption, immortality, immutability. For that reason he is also deservedly put before [or “set over as commander”] all creation.
The material is mutable. Or, rather, than which “has matter” is mutable. In coming into existence, it goes from something unformed to something formed–something with a definite shape. In contrast, that which does not “have matter,” Isidore says, is unchangeable.
This seems to me very compressed, for appears to leave open the possibility that the soul or spirit, say, is immutable, because in and of itself it is not material, when he wants to say that God himself is uniquely immutable because of his immateriality. We already know from 1.1.2, however, that the soul is in fact mutable, because it does not possess life in itself, and if God, the bestower of life, abandons it, it dies (and thus changes). Likewise, he has already asserted in 1.1.1 that everything created is mutable.
Augustine’s more fulsome exposition in his Literal Commentary on Genesis 8.20, a passage referred to by the editors of the Patrologia Latina on this passage of Isidore. There Augustine argues that the soul or created spirit is moved through time (and therefore experiences change), but not through space; the body is moved through both space and time (and therefore experiences change); but the Creator Spirit passes through neither time (he is not temporal) nor space (he is not material), and thus is immutable: spiritus creatus movet seipsum per tempus, et per tempus ac locum corpus; Spiritus autem creator movet seipsum sine tempore ac loco, movet conditum spiritum per tempus sine loco, movet corpus per tempus et locum.
Isidore goes on to say that such things as immutability are in God “substantially.” What does he mean? He means that they are not accidents in God, adjuncts of some kind to his nature. Augustine is again helpful, this time in On the Trinity 5.1 (another passage referred to by the PL editors):
What, therefore, we do not find in that which is our own best, we ought not to seek in Him who is far better than that best of ours; that so we may understand God, if we are able, and as much as we are able, as good without quality, great without quantity, a creator though He lack nothing, ruling but from no position, sustaining all things withouthavingthem, in His wholeness everywhere, yet without place, eternal without time, making things that are changeable, without change of Himself, and without passion.
We can close with a passage from Book 1 of John of Damascus’ Exposition of the Orthodox Faith, a passage that sums up much of what has been discussed in the first three posts:
All things, that exist, are either created or uncreated. If, then, things are created, it follows that they are also wholly mutable. For things, whose existence originated in change, must also be subject to change, whether it be that they perish or that they become other than they are by act of will. But if things are uncreated they must in all consistency be also wholly immutable. For things which are opposed in the nature of their existence must also be opposed in the mode of their existence, that is to say, must have opposite properties: who, then, will refuse to grant that all existing things, not only such as come within the province of the senses, but even the very angels, are subject to change and transformation and movement of various kinds? For the things appertaining to the rational world, I mean angels and spirits and demons, are subject to changes of will, whether it is a progression or a retrogression in goodness, whether a struggle or a surrender; while the others suffer changes of generation and destruction, of increase and decrease, of quality and of movement in space. Things then that are mutable are also wholly created. But things that are created must be the work of some maker, and the maker cannot have been created. For if he had been created, he also must surely have been created by some one, and so on till we arrive at something uncreated. The Creator, then, being uncreated, is also wholly immutable. And what could this be other than Deity? (Exposition 1.3)