by Aristotle
But the 'now' corresponds to the body that is carried along, as time
corresponds to the motion. For it is by means of the body that is
carried along that we become aware of the 'before and after' the
motion, and if we regard these as countable we get the 'now'. Hence in
these also the 'now' as substratum remains the same (for it is what is
before and after in movement), but what is predicated of it is
different; for it is in so far as the 'before and after' is
numerable that we get the 'now'. This is what is most knowable: for,
similarly, motion is known because of that which is moved,
locomotion because of that which is carried. what is carried is a real
thing, the movement is not. Thus what is called 'now' in one sense
is always the same; in another it is not the same: for this is true
also of what is carried.
Clearly, too, if there were no time, there would be no 'now', and
vice versa. just as the moving body and its locomotion involve each
other mutually, so too do the number of the moving body and the number
of its locomotion. For the number of the locomotion is time, while the
'now' corresponds to the moving body, and is like the unit of number.
Time, then, also is both made continuous by the 'now' and divided at
it. For here too there is a correspondence with the locomotion and the
moving body. For the motion or locomotion is made one by the thing
which is moved, because it is one-not because it is one in its own
nature (for there might be pauses in the movement of such a thing)-but
because it is one in definition: for this determines the movement as
'before' and 'after'. Here, too there is a correspondence with the
point; for the point also both connects and terminates the length-it
is the beginning of one and the end of another. But when you take it
in this way, using the one point as two, a pause is necessary, if
the same point is to be the beginning and the end. The 'now' on the
other hand, since the body carried is moving, is always different.
Hence time is not number in the sense in which there is 'number'
of the same point because it is beginning and end, but rather as the
extremities of a line form a number, and not as the parts of the
line do so, both for the reason given (for we can use the middle point
as two, so that on that analogy time might stand still), and further
because obviously the 'now' is no part of time nor the section any
part of the movement, any more than the points are parts of the
line-for it is two lines that are parts of one line.
In so far then as the 'now' is a boundary, it is not time, but an
attribute of it; in so far as it numbers, it is number; for boundaries
belong only to that which they bound, but number (e.g. ten) is the
number of these horses, and belongs also elsewhere.
It is clear, then, that time is 'number of movement in respect of
the before and after', and is continuous since it is an attribute of
what is continuous.
12
The smallest number, in the strict sense of the word 'number', is
two. But of number as concrete, sometimes there is a minimum,
sometimes not: e.g. of a 'line', the smallest in respect of
multiplicity is two (or, if you like, one), but in respect of size
there is no minimum; for every line is divided ad infinitum. Hence
it is so with time. In respect of number the minimum is one (or
two); in point of extent there is no minimum.
It is clear, too, that time is not described as fast or slow, but as
many or few and as long or short. For as continuous it is long or
short and as a number many or few, but it is not fast or slow-any more
than any number with which we number is fast or slow.
Further, there is the same time everywhere at once, but not the same
time before and after, for while the present change is one, the change
which has happened and that which will happen are different. Time is
not number with which we count, but the number of things which are
counted, and this according as it occurs before or after is always
different, for the 'nows' are different. And the number of a hundred
horses and a hundred men is the same, but the things numbered are
different-the horses from the men. Further, as a movement can be one
and the same again and again, so too can time, e.g. a year or a spring
or an autumn.
Not only do we measure the movement by the time, but also the time
by the movement, because they define each other. The time marks the
movement, since it is its number, and the movement the time. We
describe the time as much or little, measuring it by the movement,
just as we know the number by what is numbered, e.g. the number of the
horses by one horse as the unit. For we know how many horses there are
by the use of the number; and again by using the one horse as unit
we know the number of the horses itself. So it is with the time and
the movement; for we measure the movement by the time and vice
versa. It is natural that this should happen; for the movement goes
with the distance and the time with the movement, because they are
quanta and continuous and divisible. The movement has these attributes
because the distance is of this nature, and the time has them
because of the movement. And we measure both the distance by the
movement and the movement by the distance; for we say that the road is
long, if the journey is long, and that this is long, if the road is
long-the time, too, if the movement, and the movement, if the time.
Time is a measure of motion and of being moved, and it measures
the motion by determining a motion which will measure exactly the
whole motion, as the cubit does the length by determining an amount
which will measure out the whole. Further 'to be in time' means for
movement, that both it and its essence are measured by time (for
simultaneously it measures both the movement and its essence, and this
is what being in time means for it, that its essence should be
measured).
Clearly then 'to be in time' has the same meaning for other things
also, namely, that their being should be measured by time. 'To be in
time' is one of two things: (1) to exist when time exists, (2) as we
say of some things that they are 'in number'. The latter means
either what is a part or mode of number-in general, something which
belongs to number-or that things have a number.
Now, since time is number, the 'now' and the 'before' and the like
are in time, just as 'unit' and 'odd' and 'even' are in number, i.e.
in the sense that the one set belongs to number, the other to time.
But things are in time as they are in number. If this is so, they
are contained by time as things in place are contained by place.
Plainly, too, to be in time does not mean to co-exist with time, any
more than to be in motion or in place means to co-exist with motion or
place. For if 'to be in something' is to mean this, then all things
will be in anything, and the heaven will be in a grain; for when the
grain is, then also is the heaven. But this is a merely incidental
conjunction, whereas the other is necessarily involved: that which
is in time necessarily involves that there is time when it is, and
that which is in motion that there is motion when it is.
Since what is 'in time' is so in the same sense as what is in number
is so, a time greater than everything in time can be found. So it is
necessary that all the things in time should be contained by time,
just like other things also which are 'in anything', e.g. the things
'in place' by place.
A thing, then, will be affected by time, just as we are accustomed
to say that time wastes things away, and that all things grow old
through time, and that there is oblivion owing to the lapse of time,
but we do not say the same of getting to know or of becoming young
or fair. For time is by its nature the cause rather of decay, since it
is the number of change, and change removes what is.
Hence, plainly, things which are always are not, as such, in time,
for they are not contained time, nor is their being measured by
time. A proof of this is that none of them is affected by time,
which indicates that they are not in time.
Since time is the measure of motion, it will be the measure of
rest too-indirectly. For all rest is in time. For it does not follow
that what is in time is moved, though what is in motion is necessarily
moved. For time is not motion, but 'number of motion': and what is
at rest, also, can be in the number of motion. Not everything that
is not in motion can be said to be 'at rest'-but only that which can
be moved, though it actually is not moved, as was said above.
'To be in number' means that there is a number of the thing, and
that its being is measured by the number in which it is. Hence if a
thing is 'in time' it will be measured by time. But time will
measure what is moved and what is at rest, the one qua moved, the
other qua at rest; for it will measure their motion and rest
respectively.
Hence what is moved will not be measurable by the time simply in
so far as it has quantity, but in so far as its motion has quantity.
Thus none of the things which are neither moved nor at rest are in
time: for 'to be in time' is 'to be measured by time', while time is
the measure of motion and rest.
Plainly, then, neither will everything that does not exist be in
time, i.e. those non-existent things that cannot exist, as the
diagonal cannot be commensurate with the side.
Generally, if time is directly the measure of motion and
indirectly of other things, it is clear that a thing whose existence
is measured by it will have its existence in rest or motion. Those
things therefore which are subject to perishing and
becoming-generally, those which at one time exist, at another do
not-are necessarily in time: for there is a greater time which will
extend both beyond their existence and beyond the time which
measures their existence. Of things which do not exist but are
contained by time some were, e.g. Homer once was, some will be, e.g. a
future event; this depends on the direction in which time contains
them; if on both, they have both modes of existence. As to such things
as it does not contain in any way, they neither were nor are nor
will be. These are those nonexistents whose opposites always are, as
the incommensurability of the diagonal always is-and this will not
be in time. Nor will the commensurability, therefore; hence this
eternally is not, because it is contrary to what eternally is. A thing
whose contrary is not eternal can be and not be, and it is of such
things that there is coming to be and passing away.
13
The 'now' is the link of time, as has been said (for it connects
past and future time), and it is a limit of time (for it is the
beginning of the one and the end of the other). But this is not
obvious as it is with the point, which is fixed. It divides
potentially, and in so far as it is dividing the 'now' is always
different, but in so far as it connects it is always the same, as it
is with mathematical lines. For the intellect it is not always one and
the same point, since it is other and other when one divides the line;
but in so far as it is one, it is the same in every respect.
So the 'now' also is in one way a potential dividing of time, in
another the termination of both parts, and their unity. And the
dividing and the uniting are the same thing and in the same reference,
but in essence they are not the same.
So one kind of 'now' is described in this way: another is when the
time is near this kind of 'now'. 'He will come now' because he will
come to-day; 'he has come now' because he came to-day. But the
things in the Iliad have not happened 'now', nor is the flood
'now'-not that the time from now to them is not continuous, but
because they are not near.
'At some time' means a time determined in relation to the first of
the two types of 'now', e.g. 'at some time' Troy was taken, and 'at
some time' there will be a flood; for it must be determined with
reference to the 'now'. There will thus be a determinate time from
this 'now' to that, and there was such in reference to the past event.
But if there be no time which is not 'sometime', every time will be
determined.
Will time then fail? Surely not, if motion always exists. Is time
then always different or does the same time recur? Clearly time is, in
the same way as motion is. For if one and the same motion sometimes
recurs, it will be one and the same time, and if not, not.
Since the 'now' is an end and a beginning of time, not of the same
time however, but the end of that which is past and the beginning of
that which is to come, it follows that, as the circle has its
convexity and its concavity, in a sense, in the same thing, so time is
always at a beginning and at an end. And for this reason it seems to
be always different; for the 'now' is not the beginning and the end of
the same thing; if it were, it would be at the same time and in the
same respect two opposites. And time will not fail; for it is always
at a beginning.
'Presently' or 'just' refers to the part of future time which is
near the indivisible present 'now' ('When do you walk? 'Presently',
because the time in which he is going to do so is near), and to the
part of past time which is not far from the 'now' ('When do you walk?'
'I have just been walking'). But to say that Troy has just been
taken-we do not say that, because it is too far from the 'now'.
'Lately', too, refers to the part of past time which is near the
present 'now'. 'When did you go?' 'Lately', if the time is near the
existing now. 'Long ago' refers to the distant past.
'Suddenly' refers to what has departed from its former condition
in a time imperceptible because of its smallness; but it is the nature
of all change to alter things from their former condition. In time all
things come into being and pass away; for which reason some called
it the wisest of all things, but the Pythagorean Pa
ron called it the
most stupid, because in it we also forget; and his was the truer view.
It is clear then that it must be in itself, as we said before, the
condition of destruction rather than of coming into being (for change,
in itself, makes things depart from their former condition), and
only incidentally of coming into being, and of being. A sufficient
evidence of this is that nothing comes into being without itself
moving somehow and acting, but a thing can be destroyed even if it
does not move at all. And this is what, as a rule, we chiefly mean
by a thing's being destroyed by time. Still, time does not work even
this change; even this sort of change takes place incidentally in
time.
We have stated, then, that time exists and what it is, and in how
many senses we speak of the 'now', and what 'at some time',
'lately', 'presently' or 'just', 'long ago', and 'suddenly' mean.
14
These distinctions having been drawn, it is evident that every
change and everything that moves is in time; for the distinction of
faster and slower exists in reference to all change, since it is found
in every instance. In the phrase 'moving faster' I refer to that which
changes before another into the condition in question, when it moves
over the same interval and with a regular movement; e.g. in the case
of locomotion, if both things move along the circumference of a
circle, or both along a straight line; and similarly in all other
cases. But what is before is in time; for we say 'before' and
'after' with reference to the distance from the 'now', and the 'now'
is the boundary of the past and the future; so that since 'nows' are
in time, the before and the after will be in time too; for in that
in which the 'now' is, the distance from the 'now' will also be. But
'before' is used contrariwise with reference to past and to future
time; for in the past we call 'before' what is farther from the 'now',