To what genus could (movement) be reduced? It constitutes neither the
being nor the quality of the (being) in which it exists. It is not
even reducible to action, for in passion (or, experience) there are
several kinds of movements; and it is the actions and passions which
are reducible to movement. Further, movement need not necessarily be
a relative merely because movement does not exist in itself, that it
belongs to some being, and that it exists in a subject; otherwise, we
should have to classify quality also as a relation; for quality belongs
to some (being) and exists in a subject; it is not so however, with
a quantity. It might be objected that, though each of them exist in
some subject, the one by virtue of its being a quality, and the other,
of being a quantity, they themselves are not any the less species of
essences. The same argument would apply to movement; though it belong
to some subject, it is something before belonging to a subject, and
we must consider what it is in itself. Now what is relative is not
at first something by itself, and then the predicate of something
else;[416] but what is born of the relation existing between two
objects, is nothing else outside the relation to which it owes its
name; thus the double, so far as it is called doubleness, is neither
begotten, nor exists except in the comparison established between it
and a half, since, not being conceived of before, it owes its name and
its existence to the comparison thus established.