The Complete Aristotle (eng.)

sense: the natural motion
of earth is contrary inasmuch as the motion of fire is also
natural, whereas the upward motion of fire as being natural is
contrary to the downward motion of fire as being unnatural. The
same is true of the corresponding cases of remaining. But there
would seem to be a sense in which a state of rest and a motion are
opposites.]

Physics, Book VI
    Translated by R. P. Hardie and R. K. Gaye
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1
    Now if the terms ‘continuous’, ‘in contact’, and ‘in succession’
are understood as defined above things being ‘continuous’ if their
extremities are one, ‘in contact’ if their extremities are
together, and ‘in succession’ if there is nothing of their own kind
intermediate between them-nothing that is continuous can be
composed ‘of indivisibles’: e.g. a line cannot be composed of
points, the line being continuous and the point indivisible. For
the extremities of two points can neither be one (since of an
indivisible there can be no extremity as distinct from some other
part) nor together (since that which has no parts can have no
extremity, the extremity and the thing of which it is the extremity
being distinct).
    Moreover, if that which is continuous is composed of points,
these points must be either continuous or in contact with one
another: and the same reasoning applies in the case of all
indivisibles. Now for the reason given above they cannot be
continuous: and one thing can be in contact with another only if
whole is in contact with whole or part with part or part with
whole. But since indivisibles have no parts, they must be in
contact with one another as whole with whole. And if they are in
contact with one another as whole with whole, they will not be
continuous: for that which is continuous has distinct parts: and
these parts into which it is divisible are different in this way,
i.e. spatially separate.
    Nor, again, can a point be in succession to a point or a moment
to a moment in such a way that length can be composed of points or
time of moments: for things are in succession if there is nothing
of their own kind intermediate between them, whereas that which is
intermediate between points is always a line and that which is
intermediate between moments is always a period of time.
    Again, if length and time could thus be composed of
indivisibles, they could be divided into indivisibles, since each
is divisible into the parts of which it is composed. But, as we
saw, no continuous thing is divisible into things without parts.
Nor can there be anything of any other kind intermediate between
the parts or between the moments: for if there could be any such
thing it is clear that it must be either indivisible or divisible,
and if it is divisible, it must be divisible either into
indivisibles or into divisibles that are infinitely divisible, in
which case it is continuous.
    Moreover, it is plain that everything continuous is divisible
into divisibles that are infinitely divisible: for if it were
divisible into indivisibles, we should have an indivisible in
contact with an indivisible, since the extremities of things that
are continuous with one another are one and are in contact.
    The same reasoning applies equally to magnitude, to time, and to
motion: either all of these are composed of indivisibles and are
divisible into indivisibles, or none. This may be made clear as
follows. If a magnitude is composed of indivisibles, the motion
over that magnitude must be composed of corresponding indivisible
motions: e.g. if the magnitude ABG is composed of the indivisibles
A, B, G, each corresponding part of the motion DEZ of O over ABG is
indivisible. Therefore, since where there is motion there must be
something that is in motion, and where there is something in motion
there must be motion, therefore the being-moved will also be
composed of indivisibles. So O traversed A when its motion was D, B
when its motion was E, and G similarly when its motion was Z. Now a
thing that is in motion from one place to another cannot at the
moment when it was in motion both be in motion and at the same time
have completed its motion at the place to which it was in motion:
e.g. if a man is walking to Thebes, he cannot be walking to Thebes
and at the same time have completed his walk to Thebes: and, as we
saw, O traverses a the partless section A in virtue of the presence
of the motion D. Consequently, if O actually passed through A after
being in