Summa Theologica Part I, Question 10. On the Eternity of God

by William C. Michael

St. Thomas Aquinas (1225–1274)

We must now consider the eternity of God, concerning which arise six points of inquiry.

Table of Contents- Article 1. Whether This Is a Good Definition of Eternity, “The Simultaneously Whole and Perfect Possession of Interminable Life”?
- Article 2. Whether God is Eternal?
- Article 3. Whether to Be Eternal Belongs to God Alone?
- Article 4. Whether Eternity Differs from Time?
- Article 5. The Difference of Aeviternity and Time
- Article 6. Whether There Is Only One Aeviternity?

Article 1. Whether This Is a Good Definition of Eternity, “The Simultaneously Whole and Perfect Possession of Interminable Life”?

Objection 1: It seems that the definition of eternity given by Boethius (De Consol. v) is not a good one: “Eternity is the simultaneously-whole and perfect possession of interminable life.” For the word “interminable” is a negative one. But negation only belongs to what is defective, and this does not belong to eternity. Therefore in the definition of eternity the word “interminable” ought not to be found.

Obj. 2: Further, eternity signifies a certain kind of duration. But duration regards existence rather than life. Therefore the word “life” ought not to come into the definition of eternity; but rather the word “existence.”

Obj. 3: Further, a whole is what has parts. But this is alien to eternity which is simple. Therefore it is improperly said to be “whole.”

Obj. 4: Many days cannot occur together, nor can many times exist all at once. But in eternity, days and times are in the plural, for it is said, “His going forth is from the beginning, from the days of eternity” (Micah 5:2); and also it is said, “According to the revelation of the mystery hidden from eternity” (Rom. 16:25). Therefore eternity is not omni-simultaneous.

Obj. 5: Further, the whole and the perfect are the same thing. Supposing, therefore, that it is “whole,” it is superfluously described as “perfect.”

Obj. 6: Further, duration does not imply “possession.” But eternity is a kind of duration. Therefore eternity is not possession.

I answer that, As we attain to the knowledge of simple things by way of compound things, so must we reach to the knowledge of eternity by means of time, which is nothing but the numbering of movement by before and after. For since succession occurs in every movement, and one part comes after another, the fact that we reckon before and after in movement, makes us apprehend time, which is nothing else but the measure of before and after in movement. Now in a thing bereft of movement, which is always the same, there is no before or after. As therefore the idea of time consists in the numbering of before and after in movement; so likewise in the apprehension of the uniformity of what is outside of movement, consists the idea of eternity.

Further, those things are said to be measured by time which have a beginning and an end in time, because in everything which is moved there is a beginning, and there is an end. But as whatever is wholly immutable can have no succession, so it has no beginning, and no end.

Thus eternity is known from two sources: first, because what is eternal is interminable — that is, has no beginning nor end (that is, no term either way); secondly, because eternity has no succession, being simultaneously whole.

Reply Obj. 1: Simple things are usually defined by way of negation; as “a point is that which has no parts.” Yet this is not to be taken as if the negation belonged to their essence, but because our intellect which first apprehends compound things, cannot attain to the knowledge of simple things except by removing the opposite.

Reply Obj. 2: What is truly eternal, is not only being, but also living; and life extends to operation, which is not true of being. Now the protraction of duration seems to belong to operation rather than to being; hence time is the numbering of movement.

Reply Obj. 3: Eternity is called whole, not because it has parts, but because it is wanting in nothing.

Reply Obj. 4: As God, although incorporeal, is named in Scripture metaphorically by corporeal names, so eternity though simultaneously whole, is called by names implying time and succession.

Reply Obj. 5: Two things are to be considered in time: time itself, which is successive; and the “now” of time, which is imperfect. Hence the expression “simultaneously-whole” is used to remove the idea of time, and the word “perfect” is used to exclude the “now” of time.

Reply Obj. 6: Whatever is possessed, is held firmly and quietly; therefore to designate the immutability and permanence of eternity, we use the word “possession.”

Article 2. Whether God is Eternal?

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.

Obj. 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.

Obj. 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.

Obj. 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 Obj. 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 Obj. 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 Obj. 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 Obj. 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.

Article 3. Whether to Be Eternal Belongs to God Alone?

Objection 1: It seems that it does not belong to God alone to be eternal. For it is written that “those who instruct many to justice,” shall be “as stars unto perpetual eternities “ (Dan. 12:3). Now if God alone were eternal, there could not be many eternities. Therefore God alone is not the only eternal.

Obj. 2: Further, it is written “Depart, ye cursed into eternal fire” (Matt. 25:41). Therefore God is not the only eternal.

Obj. 3: Further, every necessary thing is eternal. But there are many necessary things; as, for instance, all principles of demonstration and all demonstrative propositions. Therefore God is not the only eternal.

On the contrary, Jerome says (Ep. ad Damasum, xv) that “God is the only one who has no beginning.” Now whatever has a beginning, is not eternal. Therefore God is the only one eternal.

I answer that, Eternity truly and properly so called is in God alone, because eternity follows on immutability; as appears from the first article. But God alone is altogether immutable, as was shown above (Q. 9, A. 1). Accordingly, however, as some receive immutability from Him, they share in His eternity. Thus some receive immutability from God in the way of never ceasing to exist; in that sense it is said of the earth, “it standeth for ever” (Eccl. 1:4). Again, some things are called eternal in Scripture because of the length of their duration, although they are in nature corruptible; thus (Ps. 75:5) the hills are called “eternal” and we read “of the fruits of the eternal hills.” (Deut. 33:15). Some again, share more fully than others in the nature of eternity, inasmuch as they possess unchangeableness either in being or further still in operation; like the angels, and the blessed, who enjoy the Word, because “as regards that vision of the Word, no changing thoughts exist in the Saints,” as Augustine says (De Trin. xv). Hence those who see God are said to have eternal life; according to that text, “This is eternal life, that they may know Thee the only true God,” etc. (John 17:3).

Reply Obj. 1: There are said to be many eternities, accordingly as many share in eternity, by the contemplation of God.

Reply Obj. 2: The fire of hell is called eternal, only because it never ends. Still, there is change in the pains of the lost, according to the words “To extreme heat they will pass from snowy waters” (Job 24:19). Hence in hell true eternity does not exist, but rather time; according to the text of the Psalm “Their time will be for ever” (Ps. 80:16).

Reply Obj. 3: Necessary means a certain mode of truth; and truth, according to the Philosopher (Metaph. vi), is in the mind. Therefore in this sense the true and necessary are eternal, because they are in the eternal mind, which is the divine intellect alone; hence it does not follow that anything beside God is eternal.

Article 4. Whether Eternity Differs from Time?

Objection 1: It seems that eternity does not differ from time. For two measures of duration cannot exist together, unless one is part of the other; for instance two days or two hours cannot be together; nevertheless, we may say that a day or an hour are together, considering hour as part of a day. But eternity and time occur together, each of which imports a certain measure of duration. Since therefore eternity is not a part of time, forasmuch as eternity exceeds time, and includes it, it seems that time is a part of eternity, and is not a different thing from eternity.

Obj. 2: Further, according to the Philosopher (Phys. iv), the “now” of time remains the same in the whole of time. But the nature of eternity seems to be that it is the same indivisible thing in the whole space of time. Therefore eternity is the “now” of time. But the “now” of time is not substantially different from time. Therefore eternity is not substantially different from time.

Obj. 3: Further, as the measure of the first movement is the measure of every movement, as said in Phys. iv, it thus appears that the measure of the first being is that of every being. But eternity is the measure of the first being — that is, of the divine being. Therefore eternity is the measure of every being. But the being of things corruptible is measured by time. Time therefore is either eternity or is a part of eternity.

On the contrary, Eternity is simultaneously whole. But time has a “before” and an “after.” Therefore time and eternity are not the same thing.

I answer that, It is manifest that time and eternity are not the same. Some have founded this difference on the fact that eternity has neither beginning nor an end; whereas time has a beginning and an end. This, however, makes a merely accidental, and not an absolute difference because, granted that time always was and always will be, according to the idea of those who think the movement of the heavens goes on for ever, there would yet remain a difference between eternity and time, as Boethius says (De Consol. v), arising from the fact that eternity is simultaneously whole; which cannot be applied to time: for eternity is the measure of a permanent being; while time is a measure of movement. Supposing, however, that the aforesaid difference be considered on the part of the things measured, and not as regards the measures, then there is some reason for it, inasmuch as that alone is measured by time which has beginning and end in time. Hence, if the movement of the heavens lasted always, time would not be of its measure as regards the whole of its duration, since the infinite is not measurable; but it would be the measure of that part of its revolution which has beginning and end in time.

Another reason for the same can be taken from these measures in themselves, if we consider the end and the beginning as potentialities; because, granted also that time always goes on, yet it is possible to note in time both the beginning and the end, by considering its parts: thus we speak of the beginning and the end of a day or of a year; which cannot be applied to eternity. Still these differences follow upon the essential and primary differences, that eternity is simultaneously whole, but that time is not so.

Reply Obj. 1: Such a reason would be a valid one if time and eternity were the same kind of measure; but this is seen not to be the case when we consider those things of which the respective measures are time and eternity.

Reply Obj. 2: The “now” of time is the same as regards its subject in the whole course of time, but it differs in aspect; for inasmuch as time corresponds to movement, its “now” corresponds to what is movable; and the thing movable has the same one subject in all time, but differs in aspect a being here and there; and such alteration is movement. Likewise the flow of the “now” as alternating in aspect is time. But eternity remains the same according to both subject and aspect; and hence eternity is not the same as the “now” of time.

Reply Obj. 3: As eternity is the proper measure of permanent being, so time is the proper measure of movement; and hence, according as any being recedes from permanence of being, and is subject to change, it recedes from eternity, and is subject to time. Therefore the being of things corruptible, because it is changeable, is not measured by eternity, but by time; for time measures not only things actually changed, but also things changeable; hence it not only measures movement but it also measures repose, which belongs to whatever is naturally movable, but is not actually in motion.

Article 5. The Difference of Aeviternity and Time

Objection 1: It seems that aeviternity is the same as time. For Augustine says (Gen. ad lit. viii, 20, 22, 23), that “God moves the spiritual through time.” But aeviternity is said to be the measure of spiritual substances. Therefore time is the same as aeviternity.

Obj. 2: Further, it is essential to time to have “before” and “after”; but it is essential to eternity to be simultaneously whole, as was shown above in the first article. Now aeviternity is not eternity; for it is written (Ecclus. 1:1) that eternal “Wisdom is before age.” Therefore it is not simultaneously whole but has “before” and “after”; and thus it is the same as time.

Obj. 3: Further, if there is no “before” and “after” in aeviternity, it follows that in aeviternal things there is no difference between being, having been, or going to be. Since then it is impossible for aeviternal things not to have been, it follows that it is impossible for them not to be in the future; which is false, since God can reduce them to nothing.

Obj. 4: Further, since the duration of aeviternal things is infinite as to subsequent duration, if aeviternity is simultaneously whole, it follows that some creature is actually infinite; which is impossible. Therefore aeviternity does not differ from time.

On the contrary, Boethius says (De Consol. iii) “Who commandest time to be separate from aeviternity.”

I answer that, Aeviternity differs from time, and from eternity, as the mean between them both. This difference is explained by some to consist in the fact that eternity has neither beginning nor end, aeviternity, a beginning but no end, and time both beginning and end. This difference, however, is but an accidental one, as was shown above, in the preceding article; because even if aeviternal things had always been, and would always be, as some think, and even if they might sometimes fail to be, which is possible to God to allow; even granted this, aeviternity would still be distinguished from eternity, and from time.

Others assign the difference between these three to consist in the fact that eternity has no “before” and “after”; but that time has both, together with innovation and veteration; and that aeviternity has “before” and “after” without innovation and veteration. This theory, however, involves a contradiction; which manifestly appears if innovation and veteration be referred to the measure itself. For since “before” and “after” of duration cannot exist together, if aeviternity has “before” and “after,” it must follow that with the receding of the first part of aeviternity, the after part of aeviternity must newly appear; and thus innovation would occur in aeviternity itself, as it does in time. And if they be referred to the things measured, even then an incongruity would follow. For a thing which exists in time grows old with time, because it has a changeable existence, and from the changeableness of a thing measured, there follows “before” and “after” in the measure, as is clear from Physic. iv. Therefore the fact that an aeviternal thing is neither inveterate, nor subject to innovation, comes from its changelessness; and consequently its measure does not contain “before” and “after.” We say then that since eternity is the measure of a permanent being, in so far as anything recedes from permanence of being, it recedes from eternity. Now some things recede from permanence of being, so that their being is subject to change, or consists in change; and these things are measured by time, as are all movements, and also the being of all things corruptible. But others recede less from permanence of being, forasmuch as their being neither consists in change, nor is the subject of change; nevertheless they have change annexed to them either actually or potentially. This appears in the heavenly bodies, the substantial being of which is unchangeable; and yet with unchangeable being they have changeableness of place. The same applies to the angels, who have an unchangeable being as regards their nature with changeableness as regards choice; moreover they have changeableness of intelligence, of affections and of places in their own degree. Therefore these are measured by aeviternity which is a mean between eternity and time. But the being that is measured by eternity is not changeable, nor is it annexed to change.




Mr. William C. Michael is the founding headmaster of the <a href=”">Classical Liberal Arts Academy</a>. He graduated from Rutge

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William C. Michael

William C. Michael

Mr. William C. Michael is the founding headmaster of the <a href=”">Classical Liberal Arts Academy</a>. He graduated from Rutge

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