used to denote the other categories; for instance, granted that
justice is the contrary of injustice and justice is a quality,
injustice will also be a quality: neither quantity, nor relation,
nor place, nor indeed any other category but that of quality, will
be applicable properly to injustice. So it is with all other
contraries falling under the category of quality.
Qualities admit of variation of degree. Whiteness is predicated of
one thing in a greater or less degree than of another. This is also
the case with reference to justice. Moreover, one and the same thing
may exhibit a quality in a greater degree than it did before: if a
thing is white, it may become whiter.
Though this is generally the case, there are exceptions. For if we
should say that justice admitted of variation of degree,
difficulties might ensue, and this is true with regard to all those
qualities which are dispositions. There are some, indeed, who
dispute the possibility of variation here. They maintain that
justice and health cannot very well admit of variation of degree
themselves, but that people vary in the degree in which they possess
these qualities, and that this is the case with grammatical learning
and all those qualities which are classed as dispositions. However
that may be, it is an incontrovertible fact that the things which in
virtue of these qualities are said to be what they are vary in the
degree in which they possess them; for one man is said to be better
versed in grammar, or more healthy or just, than another, and so on.
The qualities expressed by the terms 'triangular' and 'quadrangular'
do not appear to admit of variation of degree, nor indeed do any
that have to do with figure. For those things to which the
definition of the triangle or circle is applicable are all equally
triangular or circular. Those, on the other hand, to which the same
definition is not applicable, cannot be said to differ from one
another in degree; the square is no more a circle than the
rectangle, for to neither is the definition of the circle appropriate.