Are all qualities differences, or not? Whiteness, colors, qualities
perceived by touch and taste, may become differences between different
objects, though they themselves be species. But how do the sciences
of grammar or of music constitute differences? The science of grammar
renders the mind grammatical, and the science of music renders the mind
musical, especially if they be untaught; and these thus become specific
differences. Besides, we have to consider whether a difference be drawn
from the same genus (from which the considered things are drawn), or
from some other genus. If it be drawn from the same genus, it fulfils,
for the things of this genus, the same function as does a quality to
the quality to which it serves as difference. Such are virtue and
vice; virtue is a particular habit, and vice is also a particular
habit; consequently, as habits are qualities, the differences of these
habits (either of virtue or vice) will be qualities. It may perhaps be
objected that a habit without difference is not a quality, and that it
is the difference alone which constitutes the quality.[409] We will
answer that it is (commonly) said that sweet is good, and that bitter
is bad; this then implies a recognition of their difference by a habit
(a manner of being), and not by a quality.
What if sweet be said to be "crude," or thick and bitter, thin or
refined? The answer is that coarseness does not inform us of the nature
of sweetness, but indicates a manner of being of what is sweet; and
similarly, with what is refined.