'below'; and this is so, because nothing is farther from the
extremities of the universe than the region at the centre. Indeed,
it seems that in defining contraries of every kind men have recourse
to a spatial metaphor, for they say that those things are contraries
which, within the same class, are separated by the greatest possible
Quantity does not, it appears, admit of variation of degree. One
thing cannot be two cubits long in a greater degree than another.
Similarly with regard to number: what is 'three' is not more truly
three than what is 'five' is five; nor is one set of three more
truly three than another set. Again, one period of time is not said to
be more truly time than another. Nor is there any other kind of
quantity, of all that have been mentioned, with regard to which
variation of degree can be predicated. The category of quantity,
therefore, does not admit of variation of degree.
The most distinctive mark of quantity is that equality and
inequality are predicated of it. Each of the aforesaid quantities is
said to be equal or unequal. For instance, one solid is said to be
equal or unequal to another; number, too, and time can have these
terms applied to them, indeed can all those kinds of quantity that
have been mentioned.
That which is not a quantity can by no means, it would seem, be
termed equal or unequal to anything else. One particular disposition
or one particular quality, such as whiteness, is by no means
compared with another in terms of equality and inequality but rather
in terms of similarity. Thus it is the distinctive mark of quantity
that it can be called equal and unequal.