The Divine Lamp

ST. Ia, Q. 9, a. 1&2 That God is absolutely unchangeable is proved from His being the Pure Act, with no admixture of any potentiality. For the potential strictly speaking, comes after the Actual, and everything subject to change is in some degree in a state of potentiality, and capable of receiving more. Further, whatever is moved partly remains as it was, and partly goes on further, as when a thing changes from white to black, it remains in substance as it was; and hence in every change there is something which is composite; but this cannot be in God, Who is absolutely Simple. Lastly, everything moved acquires something, and attains to that which it had not; whereas God, Who is Infinite, comprehends in Himself the entire plenitude of all perfections in all beings, and cannot acquire anything more, or attain to that which He has not. He is, therefore, absolutely unchangeable. Hence, even among the ancient philosophers, truth compelled some to postulate a First Immovable Principle of all. It belongs, therefore, to God alone to be unchangeable of Himself. The creature is unchangeable through the Creator’s power, in whose hand is its existence and non-existence, for its creation and preservation depend upon the absolute Will of God. In every creature change is possible: in corruptible bodies according to their substance, and in celestial bodies according to place only, because matter’s potentiality is completed by form; hence the latter are not subject to change according to their substance, but only according to place. In the subsistent forms of the angels, who are not in potentiality to non-existence, there is a two-fold changeableness: that by which they are in potentiality to their final end, thus being subject to change as regards choice of evil instead of good; the other, according to place, whereby they can by their finite power reach to some other place. As God, therefore, is not chageable by any of these modes, He alone is absolutely unchangeable.

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Immutability

Nor is this intimate presence of God in the world to be mistaken for that tortured, twisting, developing god of the moderns that fights its way towards perfection through the struggle of the universe, changing as we change, getting better as we improve. God is altogether unchangeable. For what is change but the realization of a potentiality, the receiving of something new or the loss of something old. In God there can be no potentiality, nothing to be lost, nothing to be gained. He is pure actuality, pure being, possessing all things. He is beyond change and He alone; for He alone is first, dependent on no other, free of all potentiality.

To the modern philosopher this notion makes God completely static; if this be true, then this is a dull, stagnating, deteriorating God. His reason is not dissimilar from thc reasons for a New Yorker’s distaste for travel, an Englishman’s tolerance of the continent or an American tourist’s amusement at the strange antics of the rest of the world. In his own little world of creatures, the modern philosopher sees clearly that there must be change for progress, that immutability is closely akin to stagnation and deterioration. The point is that he is provincial enough to judge everything, even God, by the standards of that created world. It is true that change is inseparable from perfection in the world of unrealized potentialities; but it is also true that such a world is inconceivable without a Being of pure actuality, a Being Who is pure activity, Who has no potentiality, no possibility of losing or gaining but is a white flame of perfection. Such a Being is not in a state of static inertia; His is an activity so intense that change of any kind is impossible to it.- Walter Farrell A Companion To The Summa