The Complete Aristotle (eng.)

motion.
    The term ‘immovable’ we apply in the first place to that which
is absolutely incapable of being moved (just as we correspondingly
apply the term invisible to sound); in the second place to that
which is moved with difficulty after a long time or whose movement
is slow at the start-in fact, what we describe as hard to move; and
in the third place to that which is naturally designed for and
capable of motion, but is not in motion when, where, and as it
naturally would be so. This last is the only kind of immovable
thing of which I use the term ‘being at rest’: for rest is contrary
to motion, so that rest will be negation of motion in that which is
capable of admitting motion.
    The foregoing remarks are sufficient to explain the essential
nature of motion and rest, the number of kinds of change, and the
different varieties of motion.
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3
    Let us now proceed to define the terms ‘together’ and ‘apart’,
‘in contact’, ‘between’, ‘in succession’, ‘contiguous’, and
‘continuous’, and to show in what circumstances each of these terms
is naturally applicable.
    Things are said to be together in place when they are in one
place (in the strictest sense of the word ‘place’) and to be apart
when they are in different places.
    Things are said to be in contact when their extremities are
together.
    That which a changing thing, if it changes continuously in a
natural manner, naturally reaches before it reaches that to which
it changes last, is between. Thus ‘between’ implies the presence of
at least three things: for in a process of change it is the
contrary that is ‘last’: and a thing is moved continuously if it
leaves no gap or only the smallest possible gap in the material-not
in the time (for a gap in the time does not prevent things having a
‘between’, while, on the other hand, there is nothing to prevent
the highest note sounding immediately after the lowest) but in the
material in which the motion takes place. This is manifestly true
not only in local changes but in every other kind as well. (Now
every change implies a pair of opposites, and opposites may be
either contraries or contradictories; since then contradiction
admits of no mean term, it is obvious that ‘between’ must imply a
pair of contraries) That is locally contrary which is most distant
in a straight line: for the shortest line is definitely limited,
and that which is definitely limited constitutes a measure.
    A thing is ‘in succession’ when it is after the beginning in
position or in form or in some other respect in which it is
definitely so regarded, and when further there is nothing of the
same kind as itself between it and that to which it is in
succession, e.g. a line or lines if it is a line, a unit or units
if it is a unit, a house if it is a house (there is nothing to
prevent something of a different kind being between). For that
which is in succession is in succession to a particular thing, and
is something posterior: for one is not ‘in succession’ to two, nor
is the first day of the month to be second: in each case the latter
is ‘in succession’ to the former.
    A thing that is in succession and touches is ‘contiguous’. The
‘continuous’ is a subdivision of the contiguous: things are called
continuous when the touching limits of each become one and the same
and are, as the word implies, contained in each other: continuity
is impossible if these extremities are two. This definition makes
it plain that continuity belongs to things that naturally in virtue
of their mutual contact form a unity. And in whatever way that
which holds them together is one, so too will the whole be one,
e.g. by a rivet or glue or contact or organic union.
    It is obvious that of these terms ‘in succession’ is first in
order of analysis: for that which touches is necessarily in
succession, but not everything that is in succession touches: and
so succession is a property of things prior in definition, e.g.
numbers, while contact is not. And if there is continuity there is
necessarily contact, but if there is contact, that alone does not
imply continuity: for the extremities of things may be ‘together’
without necessarily being one: but they cannot be one without being
necessarily together. So natural junction is last in coming to be:
for the extremities must necessarily come into contact if they are
to be naturally joined: but things that are in