1. Next he asks whether God alone is immutable. The importance of this article is fairly important, as it establishes the means by which God’s relation to time will be distinguished from that of other creatures in the subsequent question. He provides three objections.
2. First, he appeals to the immobility of immaterial substances (angels, souls). Second, he observes that whatever has reached its ultimate end is incapable of motion. Third, he cites the book of Six Principles, which says that abstract forms are invariable (whereas only the things subject to them change).
3. The Sed Contra cites Augustine’s book On the Nature of the Good.
4. In the Corpus he lays out a sort of hierarchy of mutability. First he distinguishes between what is mutable by its own power and by the power of another. All creatures are mutable by the power of God, since it was by God’s power that they come to be. All creatures are also mutable by their own power, since in each creature there is a composition of potency and act, and thus the power to attain its end.
5. But here again he divides mutability into two classes: some things have mutability as regards their own power to exist, and others do not. In the second group are angels and other spiritual substances, which, lacking material composition, have no potency to decompose: their existence is supplied by God and sustained by God and cannot pass substantially from one form into another, because they are nothing but their forms, which they exhaust. (More will be said on this later on.) But most things that we encounter do have mutability as concerns their power to exist, because material things can change substantial forms, i.e. can lose the form that unite them and give them their species, and become different things altogether. Note that this is not true in spiritual beings, because they are nothing but their forms. Still, among spiritual beings there is a further kind of mutability, in that they can choose between good and evil, make themselves present in one place or another, and apply their powers to particular things.
6. He also gives a short discourse on the degrees of separability in accidents, i.e. the extent to which different sorts of accidents can be removed from the subject they inhere in without destroying the subject altogether.
7. To summarize: every creature is mutable both by the power of God, in whose freedom it lies to cause them to exist or cease to exist, and by their own power: either to continue existing or to decompose into another, or to extend its power to a particular object, or to attain its end.
8. He replies to the objections very briefly: First, only material things are mobile in terms of locomotion. Immaterial forms can be mobile in other ways. Second, even though good Angels and the Saints in heaven are given sufficient grace that their election is indefectible, there are other ways in which they can move, despite having achieved their end. Third, forms are invariable in themselves, abstractly, but on account of them (having them or not having them) the subjects in which they inhere are variable.
OUTLINE OF ARTICLE
- Immaterial substances are immobile and therefore immutable.
- Things that have reached their end are immutable.
- Forms are invariable and therefore immutable.
- Things are mutable either by their own power or by the power of another.
- In the second way, everything is mutable except God, because everything is created by him.
- In the first way, things are mutable either as to their existence or as to their operation.
- As to their existence only material things are mutable.
- As to their operation, everything is mutable, including angels.
- Immaterial substances are mobile, but not by locomotion.
- Immutable as regards their end, but not in other ways.
- Forms are immutable in abstract, but they vary by their subjects.