which are accidental either to the same subject or to one another,
do not combine to form a unity. Take the proposition 'man is white
of complexion and musical'. Whiteness and being musical do not
coalesce to form a unity, for they belong only accidentally to the
same subject. Nor yet, if it were true to say that that which is white
is musical, would the terms 'musical' and 'white' form a unity, for it
is only incidentally that that which is musical is white; the
combination of the two will, therefore, not form a unity.
Thus, again, whereas, if a man is both good and a shoemaker, we
cannot combine the two propositions and say simply that he is a good
shoemaker, we are, at the same time, able to combine the predicates
'animal' and 'biped' and say that a man is an animal with two feet,
for these predicates are not accidental.
Those predicates, again, cannot form a unity, of which the one is
implicit in the other: thus we cannot combine the predicate 'white'
again and again with that which already contains the notion 'white',
nor is it right to call a man an animal-man or a two-footed man; for
the notions 'animal' and 'biped' are implicit in the word 'man'. On
the other hand, it is possible to predicate a term simply of any one
instance, and to say that some one particular man is a man or that
some one white man is a white man.
Yet this is not always possible: indeed, when in the adjunct there
is some opposite which involves a contradiction, the predication of
the simple term is impossible. Thus it is not right to call a dead man
a man. When, however, this is not the case, it is not impossible.
Yet the facts of the case might rather be stated thus: when some
such opposite elements are present, resolution is never possible,
but when they are not present, resolution is nevertheless not always
possible. Take the proposition 'Homer is so-and-so', say 'a poet';
does it follow that Homer is, or does it not? The verb 'is' is here
used of Homer only incidentally, the proposition being that Homer is a
poet, not that he is, in the independent sense of the word.