[
1068a]
[1]
And since every motion is a kind of change,
and the three kinds of change are those which we have described,
1 and of these
those which relate to generation and destruction are not motions, and
these are the changes between contradictories, the change from
positive to positive must alone be motion. The subjects are either
contraries or intermediates (for privative terms may also be regarded
as contraries) and are denoted by a positive term—e.g.
"naked" or "toothless" or "black."
Now since the
categories are distinguished as substance, quality, place, activity or
passivity, relation and quantity,
2 there must be three kinds of motion, in respect of
quality, quantity and place. There is no motion
3 in respect of substance, because substance has no
contrary; nor of the relative, because it is possible that when one of
two related things changes the relation to it of the other thing, even
though the thing itself does not change, may become untrue; therefore
the motion of these related things is accidental.Nor is there motion of the agent or
patient, or of the mover and the thing moved, because there is no
motion of motion nor no generation of generation, nor in general is
there change of change. There are two ways in which there might be
motion of motion: (1) Motion might be the subject of motion, as, e.g.,
a man is moved because he changes from white to black; in this way
motion might be heated or cooled or might change its place or
increase.
[20]
But this is impossible,
because the change is not a subject. Or (2) some other subject might
change from change to some other form of existence, as, e.g., a man
changes from sickness to health. But this is also impossible except
accidentally.Every
motion is a change from one thing into something else; and the same is
true of generation and destruction, except that these are changes into
opposites in one sense,
4 while the other, i.e. motion, is a
change into opposites in another sense.
5 Hence a thing changes at
the same time from health to sickness, and from this change itself
into another.Now clearly
if it has fallen ill it will be already changed (for it cannot remain
at rest) into that other change, whatever it may be; and further this
cannot be, in any given case, any chance change; and it also must be
from something into something else. Therefore it will be the opposite
change, viz. becoming healthy. But this is so accidentally; just as
there is change from recollecting to forgetting because the
subject changes, now in the direction of knowledge
and now in that of ignorance.
Further, we shall have an
infinite series if there is to be change of change and becoming of
becoming, because if the latter of two becomings comes to be from the
former, the former must come to be too.