Thomas Aquinas, Summa Theologiae

Objection 1: It seems that God is not eternal. For nothing made can be predicated of God; for Boethius says (De Trin. iv) that, "The now that flows away makes time, the now that stands still makes eternity;" and Augustine says (Octog. Tri. Quaest. qu. 28) "that God is the author of eternity." Therefore God is not eternal.

Objection 2: Further, what is before eternity, and after eternity, is not measured by eternity. But, as Aristotle says (De Causis), "God is before eternity and He is after eternity": for it is written that "the Lord shall reign for eternity, and beyond " (Ex. 15:18). Therefore to be eternal does not belong to God.

Objection 3: Further, eternity is a kind of measure. But to be measured belongs not to God. Therefore it does not belong to Him to be eternal.

Objection 4: Further, in eternity, there is no present, past or future, since it is simultaneously whole; as was said in the preceding article. But words denoting present, past and future time are applied to God in Scripture. Therefore God is not eternal.

On the contrary, Athanasius says in his Creed: "The Father is eternal, the Son is eternal, the Holy Ghost is eternal."

I answer that, The idea of eternity follows immutability, as the idea of time follows movement, as appears from the preceding article. Hence, as God is supremely immutable, it supremely belongs to Him to be eternal. Nor is He eternal only; but He is His own eternity; whereas, no other being is its own duration, as no other is its own being. Now God is His own uniform being; and hence as He is His own essence, so He is His own eternity.

Reply to Objection 1: The "now" that stands still, is said to make eternity according to our apprehension. As the apprehension of time is caused in us by the fact that we apprehend the flow of the "now," so the apprehension of eternity is caused in us by our apprehending the "now" standing still. When Augustine says that "God is the author of eternity," this is to be understood of participated eternity. For God communicates His eternity to some in the same way as He communicates His immutability.

Reply to Objection 2: From this appears the answer to the Second Objection. For God is said to be before eternity, according as it is shared by immaterial substances. Hence, also, in the same book, it is said that "intelligence is equal to eternity." In the words of Exodus, "The Lord shall reign for eternity, and beyond," eternity stands for age, as another rendering has it. Thus it is said that the Lord will reign beyond eternity, inasmuch as He endures beyond every age, i.e. beyond every kind of duration. For age is nothing more than the period of each thing, as is said in the book De Coelo i. Or to reign beyond eternity can be taken to mean that if any other thing were conceived to exist for ever, as the movement of the heavens according to some philosophers, then God would still reign beyond, inasmuch as His reign is simultaneously whole.

Reply to Objection 3: Eternity is nothing else but God Himself. Hence God is not called eternal, as if He were in any way measured; but the idea of measurement is there taken according to the apprehension of our mind alone.

Reply to Objection 4: Words denoting different times are applied to God, because His eternity includes all times; not as if He Himself were altered through present, past and future.

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod deus non sit aeternus.

Nihil enim factum potest dici de deo. Sed aeternitas est aliquid factum, dicit enim boetius quod nunc fluens facit tempus, nunc stans facit aeternitatem; et Augustinus dicit, in libro octoginta trium quaest., quod deus est auctor aeternitatis.

Ergo deus non est aeternus.

Argumentum 2

Praeterea, quod est ante aeternitatem et post aeternitatem, non mensuratur aeternitate.

Sed deus est ante aeternitatem, ut dicitur in libro de causis, et post aeternitatem; dicitur enim Exod. XV, quod dominus regnabit in aeternum et ultra.

Ergo esse aeternum non convenit deo.

Argumentum 3

Praeterea, aeternitas mensura quaedam est. Sed deo non convenit esse mensuratum. Ergo non competit ei esse aeternum.

Argumentum 4

Praeterea, in aeternitate non est praesens, praeteritum vel futurum cum sit tota simul, ut dictum est.

Sed de deo dicuntur in Scripturis verba praesentis temporis, praeteriti vel futuri.

Ergo deus non est aeternus.

Sed Contra

Sed contra est quod dicit Athanasius, aeternus pater, aeternus filius, aeternus spiritus sanctus.

Corpus

Respondeo dicendum quod ratio aeternitatis consequitur immutabilitatem, sicut ratio temporis consequitur motum, ut ex dictis patet.

Unde, cum deus sit maxime immutabilis, sibi maxime competit esse aeternum. Nec solum est aeternus, sed est sua aeternitas, cum tamen nulla alia res sit sua duratio, quia non est suum esse. Deus autem est suum esse uniforme, unde, sicut est sua essentia, ita est sua aeternitas.

Ad 1

Ad primum ergo dicendum quod nunc stans dicitur facere aeternitatem, secundum nostram apprehensionem. Sicut enim causatur in nobis apprehensio temporis, eo quod apprehendimus fluxum ipsius nunc, ita causatur in nobis apprehensio aeternitatis, inquantum apprehendimus nunc stans.

Quod autem dicit Augustinus, quod deus est auctor aeternitatis, intelligitur de aeternitate participata, eo enim modo communicat deus suam aeternitatem aliquibus, quo et suam immutabilitatem.

Ad 2

Et per hoc patet solutio ad secundum. Nam deus dicitur esse ante aeternitatem, prout participatur a substantiis immaterialibus. Unde et ibidem dicitur, quod intelligentia parificatur aeternitati.

Quod autem dicitur in exodo, dominus regnabit in aeternum et ultra sciendum quod aeternum accipitur ibi pro saeculo, sicut habet alia translatio. Sic igitur dicitur quod regnabit ultra aeternum, quia durat ultra quodcumque saeculum, idest ultra quamcumque durationem datam, nihil est enim aliud saeculum quam periodus cuiuslibet rei, ut dicitur in libro I de caelo.

Vel dicitur etiam ultra aeternum regnare, quia, si etiam aliquid aliud semper esset (ut motus caeli secundum quosdam philosophos), tamen deus ultra regnat, inquantum eius regnum est totum simul.

Ad 3

Ad tertium dicendum quod aeternitas non est aliud quam ipse deus.

Unde non dicitur deus aeternus, quasi sit aliquo modo mensuratus, sed accipitur ibi ratio mensurae secundum apprehensionem nostram tantum.

Ad 4

Ad quartum dicendum quod verba diversorum temporum attribuuntur deo, inquantum eius aeternitas omnia tempora includit, non quod ipse varietur per praesens, praeteritum et futurum.