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.
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