we call men good boxers or runners, or healthy or sickly: in fact it
includes all those terms which refer to inborn capacity or incapacity.
Such things are not predicated of a person in virtue of his
disposition, but in virtue of his inborn capacity or incapacity to
do something with ease or to avoid defeat of any kind. Persons are
called good boxers or good runners, not in virtue of such and such a
disposition, but in virtue of an inborn capacity to accomplish
something with ease. Men are called healthy in virtue of the inborn
capacity of easy resistance to those unhealthy influences that may
ordinarily arise; unhealthy, in virtue of the lack of this capacity.
Similarly with regard to softness and hardness. Hardness is predicated
of a thing because it has that capacity of resistance which enables it
to withstand disintegration; softness, again, is predicated of a thing
by reason of the lack of that capacity.
A third class within this category is that of affective qualities
and affections. Sweetness, bitterness, sourness, are examples of
this sort of quality, together with all that is akin to these; heat,
moreover, and cold, whiteness, and blackness are affective
qualities. It is evident that these are qualities, for those things
that possess them are themselves said to be such and such by reason of
their presence. Honey is called sweet because it contains sweetness;
the body is called white because it contains whiteness; and so in
all other cases.
The term 'affective quality' is not used as indicating that those
things which admit these qualities are affected in any way. Honey is
not called sweet because it is affected in a specific way, nor is this
what is meant in any other instance. Similarly heat and cold are
called affective qualities, not because those things which admit
them are affected. What is meant is that these said qualities are
capable of producing an 'affection' in the way of perception. For
sweetness has the power of affecting the sense of taste; heat, that of
touch; and so it is with the rest of these qualities.