The Complete Aristotle (eng.)

least being thus needed to
determine its presence: consequently that in which a thing is at
rest cannot be without parts. Since, then it is divisible, it must
be a period of time, and the thing must be at rest in every one of
its parts, as may be shown by the same method as that used above in
similar demonstrations.
    So there can be no primary part of the time: and the reason is
that rest and motion are always in a period of time, and a period
of time has no primary part any more than a magnitude or in fact
anything continuous: for everything continuous is divisible into an
infinite number of parts.
    And since everything that is in motion is in motion in a period
of time and changes from something to something, when its motion is
comprised within a particular period of time essentially-that is to
say when it fills the whole and not merely a part of the time in
question-it is impossible that in that time that which is in motion
should be over against some particular thing primarily. For if a
thing-itself and each of its parts-occupies the same space for a
definite period of time, it is at rest: for it is in just these
circumstances that we use the term ‘being at rest’-when at one
moment after another it can be said with truth that a thing, itself
and its parts, occupies the same space. So if this is being at rest
it is impossible for that which is changing to be as a whole, at
the time when it is primarily changing, over against any particular
thing (for the whole period of time is divisible), so that in one
part of it after another it will be true to say that the thing,
itself and its parts, occupies the same space. If this is not so
and the aforesaid proposition is true only at a single moment, then
the thing will be over against a particular thing not for any
period of time but only at a moment that limits the time. It is
true that at any moment it is always over against something
stationary: but it is not at rest: for at a moment it is not
possible for anything to be either in motion or at rest. So while
it is true to say that that which is in motion is at a moment not
in motion and is opposite some particular thing, it cannot in a
period of time be over against that which is at rest: for that
would involve the conclusion that that which is in locomotion is at
rest.
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9
    Zeno’s reasoning, however, is fallacious, when he says that if
everything when it occupies an equal space is at rest, and if that
which is in locomotion is always occupying such a space at any
moment, the flying arrow is therefore motionless. This is false,
for time is not composed of indivisible moments any more than any
other magnitude is composed of indivisibles.
    Zeno’s arguments about motion, which cause so much disquietude
to those who try to solve the problems that they present, are four
in number. The first asserts the non-existence of motion on the
ground that that which is in locomotion must arrive at the half-way
stage before it arrives at the goal. This we have discussed
above.
    The second is the so-called ‘Achilles’, and it amounts to this,
that in a race the quickest runner can never overtake the slowest,
since the pursuer must first reach the point whence the pursued
started, so that the slower must always hold a lead. This argument
is the same in principle as that which depends on bisection, though
it differs from it in that the spaces with which we successively
have to deal are not divided into halves. The result of the
argument is that the slower is not overtaken: but it proceeds along
the same lines as the bisection-argument (for in both a division of
the space in a certain way leads to the result that the goal is not
reached, though the ‘Achilles’ goes further in that it affirms that
even the quickest runner in legendary tradition must fail in his
pursuit of the slowest), so that the solution must be the same. And
the axiom that that which holds a lead is never overtaken is false:
it is not overtaken, it is true, while it holds a lead: but it is
overtaken nevertheless if it is granted that it traverses the
finite distance prescribed. These then are two of his
arguments.
    The third is that already given above, to the effect that the
flying arrow is at rest, which result follows from the assumption
that time is composed of moments: if this assumption is not
granted, the conclusion will not follow.
    The fourth argument is that concerning the two rows of bodies,
each