The Complete Aristotle (eng.)

which the first is that which is in
motion, the second is that to which the motion proceeds, and the
third is that from which it proceeds. This being so, it is clear
that the motion is in the wood, not in its form: for the motion is
neither caused nor experienced by the form or the place or the
quantity. So we are left with a mover, a moved, and a goal of
motion. I do not include the starting-point of motion: for it is
the goal rather than the starting-point of motion that gives its
name to a particular process of change. Thus ‘perishing’ is change
to not-being, though it is also true that that that which perishes
changes from being: and ‘becoming’ is change to being, though it is
also change from not-being.
    Now a definition of motion has been given above, from which it
will be seen that every goal of motion, whether it be a form, an
affection, or a place, is immovable, as, for instance, knowledge
and heat. Here, however, a difficulty may be raised. Affections, it
may be said, are motions, and whiteness is an affection: thus there
may be change to a motion. To this we may reply that it is not
whiteness but whitening that is a motion. Here also the same
distinctions are to be observed: a goal of motion may be so
accidentally, or partially and with reference to something other
than itself, or directly and with no reference to anything else:
for instance, a thing which is becoming white changes accidentally
to an object of thought, the colour being only accidentally the
object of thought; it changes to colour, because white is a part of
colour, or to Europe, because Athens is a part of Europe; but it
changes essentially to white colour. It is now clear in what sense
a thing is in motion essentially, accidentally, or in respect of
something other than itself, and in what sense the phrase ‘itself
directly’ is used in the case both of the mover and of the moved:
and it is also clear that the motion is not in the form but in that
which is in motion, that is to say ‘the movable in activity’. Now
accidental change we may leave out of account: for it is to be
found in everything, at any time, and in any respect. Change which
is not accidental on the other hand is not to be found in
everything, but only in contraries, in things intermediate
contraries, and in contradictories, as may be proved by induction.
An intermediate may be a starting-point of change, since for the
purposes of the change it serves as contrary to either of two
contraries: for the intermediate is in a sense the extremes. Hence
we speak of the intermediate as in a sense a contrary relatively to
the extremes and of either extreme as a contrary relatively to the
intermediate: for instance, the central note is low relatively-to
the highest and high relatively to the lowest, and grey is light
relatively to black and dark relatively to white.
    And since every change is from something to something-as the
word itself (metabole) indicates, implying something ‘after’ (meta)
something else, that is to say something earlier and something
later-that which changes must change in one of four ways: from
subject to subject, from subject to nonsubject, from non-subject to
subject, or from non-subject to non-subject, where by ‘subject’ I
mean what is affirmatively expressed. So it follows necessarily
from what has been said above that there are only three kinds of
change, that from subject to subject, that from subject to
non-subject, and that from non-subject to subject: for the fourth
conceivable kind, that from non-subject to nonsubject, is not
change, as in that case there is no opposition either of contraries
or of contradictories.
    Now change from non-subject to subject, the relation being that
of contradiction, is ‘coming to be’-’unqualified coming to be’ when
the change takes place in an unqualified way, ‘particular coming to
be’ when the change is change in a particular character: for
instance, a change from not-white to white is a coming to be of the
particular thing, white, while change from unqualified not-being to
being is coming to be in an unqualified way, in respect of which we
say that a thing ‘comes to be’ without qualification, not that it
‘comes to be’ some particular thing. Change from subject to
non-subject is ‘perishing’-’unqualified perishing’ when the change
is from being to not-being, ‘particular perishing’ when the change
is to the opposite negation, the distinction being the same as that
made