Thomas Aquinas, Summa Theologiae

Objection 1: It seems that to be immutable does not belong to God alone. For the Philosopher says (Metaph. ii) that "matter is in everything which is moved." But, according to some, certain created substances, as angels and souls, have not matter. Therefore to be immutable does not belong to God alone.

Objection 2: Further, everything in motion moves to some end. What therefore has already attained its ultimate end, is not in motion. But some creatures have already attained to their ultimate end; as all the blessed in heaven. Therefore some creatures are immovable.

Objection 3: Further, everything which is mutable is variable. But forms are invariable; for it is said (Sex Princip. i) that "form is essence consisting of the simple and invariable." Therefore it does not belong to God alone to be immutable.

On the contrary, Augustine says (De Nat. Boni. i), "God alone is immutable; and whatever things He has made, being from nothing, are mutable."

I answer that, God alone is altogether immutable; whereas every creature is in some way mutable. Be it known therefore that a mutable thing can be called so in two ways: by a power in itself; and by a power possessed by another. For all creatures before they existed, were possible, not by any created power, since no creature is eternal, but by the divine power alone, inasmuch as God could produce them into existence. Thus, as the production of a thing into existence depends on the will of God, so likewise it depends on His will that things should be preserved; for He does not preserve them otherwise than by ever giving them existence; hence if He took away His action from them, all things would be reduced to nothing, as appears from Augustine (Gen. ad lit. iv, 12). Therefore as it was in the Creator's power to produce them before they existed in themselves, so likewise it is in the Creator's power when they exist in themselves to bring them to nothing. In this way therefore, by the power of another---namely, of God---they are mutable, inasmuch as they are producible from nothing by Him, and are by Him reducible from existence to non-existence.

If, however, a thing is called mutable by a power in itself, thus also in some manner every creature is mutable. For every creature has a twofold power, active and passive; and I call that power passive which enables anything to attain its perfection either in being, or in attaining to its end. Now if the mutability of a thing be considered according to its power for being, in that way all creatures are not mutable, but those only in which what is potential in them is consistent with non-being. Hence, in the inferior bodies there is mutability both as regards substantial being, inasmuch as their matter can exist with privation of their substantial form, and also as regards their accidental being, supposing the subject to coexist with privation of accident; as, for example, this subject "man" can exist with "not-whiteness" and can therefore be changed from white to not-white. But supposing the accident to be such as to follow on the essential principles of the subject, then the privation of such an accident cannot coexist with the subject. Hence the subject cannot be changed as regards that kind of accident; as, for example, snow cannot be made black. Now in the celestial bodies matter is not consistent with privation of form, because the form perfects the whole potentiality of the matter; therefore these bodies are not mutable as to substantial being, but only as to locality, because the subject is consistent with privation of this or that place. On the other hand incorporeal substances, being subsistent forms which, although with respect to their own existence are as potentiality to act, are not consistent with the privation of this act; forasmuch as existence is consequent upon form, and nothing corrupts except it lose its form. Hence in the form itself there is no power to non-existence; and so these kinds of substances are immutable and invariable as regards their existence. Wherefore Dionysius says (Div. Nom. iv) that "intellectual created substances are pure from generation and from every variation, as also are incorporeal and immaterial substances." Still, there remains in them a twofold mutability: one as regards their potentiality to their end; and in that way there is in them a mutability according to choice from good to evil, as Damascene says (De Fide ii, 3,4); the other as regards place, inasmuch as by their finite power they attain to certain fresh places---which cannot be said of God, who by His infinity fills all places, as was shown above (Question 8, Article 2).

Thus in every creature there is a potentiality to change either as regards substantial being as in the case of things corruptible; or as regards locality only, as in the case of the celestial bodies; or as regards the order to their end, and the application of their powers to divers objects, as in the case with the angels; and universally all creatures generally are mutable by the power of the Creator, in Whose power is their existence and non-existence. Hence since God is in none of these ways mutable, it belongs to Him alone to be altogether immutable.

Reply to Objection 1: This objection proceeds from mutability as regards substantial or accidental being; for philosophers treated of such movement.

Reply to Objection 2: The good angels, besides their natural endowment of immutability of being, have also immutability of election by divine power; nevertheless there remains in them mutability as regards place.

Reply to Objection 3: Forms are called invariable, forasmuch as they cannot be subjects of variation; but they are subject to variation because by them their subject is variable. Hence it is clear that they vary in so far as they are; for they are not called beings as though they were the subject of being, but because through them something has being.

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod esse immutabile non sit proprium dei.

Dicit enim philosophus, in II metaphys., quod materia est in omni eo quod movetur.

Sed substantiae quaedam creatae, sicut Angeli et animae, non habent materiam, ut quibusdam videtur.

Ergo esse immutabile non est proprium dei.

Argumentum 2

Praeterea, omne quod movetur, movetur propter aliquem finem, quod ergo iam pervenit ad ultimum finem, non movetur. Sed quaedam creaturae iam pervenerunt ad ultimum finem, sicut omnes beati.

Ergo aliquae creaturae sunt immobiles.

Argumentum 3

Praeterea, omne quod est mutabile, est variabile. Sed formae sunt invariabiles, dicitur enim in libro sex principiorum, quod forma est simplici et invariabili essentia consistens.

Ergo non est solius dei proprium esse immutabile.

Sed Contra

Sed contra est quod dicit Augustinus, in libro de natura boni, solus deus immutabilis est; quae autem fecit, quia ex nihilo sunt, mutabilia sunt.

Corpus

Respondeo dicendum quod solus deus est omnino immutabilis, omnis autem creatura aliquo modo est mutabilis. Sciendum est enim quod mutabile potest aliquid dici dupliciter, uno modo, per potentiam quae in ipso est; alio modo, per potentiam quae in altero est. Omnes enim creaturae, antequam essent, non erant possibiles esse per aliquam potentiam creatam, cum nullum creatum sit aeternum, sed per solam potentiam divinam, inquantum deus poterat eas in esse producere. Sicut autem ex voluntate dei dependet quod res in esse producit, ita ex voluntate eius dependet quod res in esse conservat, non enim aliter eas in esse conservat, quam semper eis esse dando; unde si suam actionem eis subtraheret, omnia in nihilum redigerentur, ut patet per Augustinum, IV super Gen. Ad litt..

Sicut igitur in potentia creatoris fuit ut res essent, antequam essent in seipsis, ita in potentia creatoris est, postquam sunt in seipsis, ut non sint. Sic igitur per potentiam quae est in altero, scilicet in deo, sunt mutabiles, inquantum ab ipso ex nihilo potuerunt produci in esse, et de esse possunt reduci in non esse.

Si autem dicatur aliquid mutabile per potentiam in ipso existentem, sic etiam aliquo modo omnis creatura est mutabilis. Est enim in creatura duplex potentia, scilicet activa et passiva. Dico autem potentiam passivam, secundum quam aliquid assequi potest suam perfectionem, vel in essendo vel in consequendo finem. Si igitur attendatur mutabilitas rei secundum potentiam ad esse, sic non in omnibus creaturis est mutabilitas, sed in illis solum in quibus illud quod est possibile in eis, potest stare cum non esse. Unde in corporibus inferioribus est mutabilitas et secundum esse substantiale, quia materia eorum potest esse cum privatione formae substantialis ipsorum, et quantum ad esse accidentale, si subiectum compatiatur secum privationem accidentis; sicut hoc subiectum, homo, compatitur secum non album, et ideo potest mutari de albo in non album. Si vero sit tale accidens quod consequatur principia essentialia subiecti, privatio illius accidentis non potest stare cum subiecto, unde subiectum non potest mutari secundum illud accidens, sicut nix non potest fieri nigra.

In corporibus vero caelestibus, materia non compatitur secum privationem formae, quia forma perficit totam potentialitatem materiae, et ideo non sunt mutabilia secundum esse substantiale; sed secundum esse locale, quia subiectum compatitur secum privationem huius loci vel illius. Substantiae vero incorporeae, quia sunt ipsae formae subsistentes, quae tamen se habent ad esse ipsarum sicut potentia ad actum, non compatiuntur secum privationem huius actus, quia esse consequitur formam, et nihil corrumpitur nisi per hoc quod amittit formam. Unde in ipsa forma non est potentia ad non esse, et ideo huiusmodi substantiae sunt immutabiles et invariabiles secundum esse.

Et hoc est quod dicit dionysius, IV cap. De div. Nom., quod substantiae intellectuales creatae mundae sunt a generatione et ab omni variatione, sicut incorporales et immateriales.

Sed tamen remanet in eis duplex mutabilitas. Una secundum quod sunt in potentia ad finem, et sic est in eis mutabilitas secundum electionem de bono in malum, ut Damascenus dicit.

Alia secundum locum, inquantum virtute sua finita possunt attingere quaedam loca quae prius non attingebant, quod de deo dici non potest, qui sua infinitate omnia loca replet, ut supra dictum est.

Sic igitur in omni creatura est potentia ad mutationem, vel secundum esse substantiale, sicut corpora corruptibilia; vel secundum esse locale tantum, sicut corpora caelestia, vel secundum ordinem ad finem et applicationem virtutis ad diversa, sicut in Angelis. Et universaliter omnes creaturae communiter sunt mutabiles secundum potentiam creantis, in cuius potestate est esse et non esse earum.

Unde, cum deus nullo istorum modorum sit mutabilis, proprium eius est omnino immutabilem esse.

Ad 1

Ad primum ergo dicendum quod obiectio illa procedit de eo quod est mutabile secundum esse substantiale vel accidentale, de tali enim motu philosophi tractaverunt.

Ad 2

Ad secundum dicendum quod Angeli boni, supra immutabilitatem essendi, quae competit eis secundum naturam, habent immutabilitatem electionis ex divina virtute, tamen remanet in eis mutabilitas secundum locum.

Ad 3

Ad tertium dicendum quod formae dicuntur invariabiles, quia non possunt esse subiectum variationis, subiiciuntur tamen variationi, inquantum subiectum secundum eas variatur. Unde patet quod secundum quod sunt, sic variantur, non enim dicuntur entia quasi sint subiectum essendi, sed quia eis aliquid est.