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.