The Complete Aristotle (eng.)

is not derived from that of any quality; for lob
those capacities have no name assigned to them. In this, the inborn
capacity is distinct from the science, with reference to which men
are called, e.g. boxers or wrestlers. Such a science is classed as
a disposition; it has a name, and is called ‘boxing’ or ‘wrestling’
as the case may be, and the name given to those disposed in this
way is derived from that of the science. Sometimes, even though a
name exists for the quality, that which takes its character from
the quality has a name that is not a derivative. For instance, the
upright man takes his character from the possession of the quality
of integrity, but the name given him is not derived from the word
‘integrity’. Yet this does not occur often.
    We may therefore state that those things are said to be
possessed of some specific quality which have a name derived from
that of the aforesaid quality, or which are in some other way
dependent on it.
    One quality may be the contrary of another; thus justice is the
contrary of injustice, whiteness of blackness, and so on. The
things, also, which are said to be such and such in virtue of these
qualities, may be contrary the one to the other; for that which is
unjust is contrary to that which is just, that which is white to
that which is black. This, however, is not always the case. Red,
yellow, and such colours, though qualities, have no contraries.
    If one of two contraries is a quality, the other will also be a
quality. This will be evident from particular instances, if we
apply the names 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. In short, if the definition of the term proposed is
not applicable to both objects, they cannot be compared. Thus it is
not all qualities which admit of variation of degree.
    Whereas none of the characteristics I have mentioned are
peculiar to quality, the fact that likeness and unlikeness can be
predicated with reference to quality only, gives to that category
its distinctive feature. One thing is like another only with
reference to that in virtue of which it is such and such; thus this
forms the peculiar mark of quality.
    We must not be disturbed because it may be argued that, though
proposing to discuss the category of quality, we have included in
it many relative terms. We did say that habits and dispositions
were relative. In practically all such cases the genus is relative,
the individual not. Thus knowledge, as a genus, is explained