at the time at which, it should naturally be present. We do not
call that toothless which has not teeth, or that blind which has
not sight, but rather that which has not teeth or sight at the
time when by nature it should. For there are some creatures which
from birth are without sight, or without teeth, but these are not
called toothless or blind.

To be without some faculty or to possess it is not the same as
the corresponding 'privative' or 'positive'. 'Sight' is a
'positive', 'blindness' a 'privative', but 'to possess sight' is
not equivalent to 'sight', 'to be blind' is not equivalent to
'blindness'. Blindness is a 'privative', to be blind is to be in
a state of privation, but is not a 'privative'. Moreover, if
'blindness' were equivalent to 'being blind', both would be
predicated of the same subject; but though a man is said to be
blind, he is by no means said to be blindness.

To be in a state of 'possession' is, it appears, the opposite of
being in a state of 'privation', just as 'positives' and
'privatives' themselves are opposite. There is the same type of
antithesis in both cases; for just as blindness is opposed to
sight, so is being blind opposed to having sight.

That which is affirmed or denied is not itself affirmation or
denial. By 'affirmation' we mean an affirmative proposition, by
'denial' a negative. Now, those facts which form the matter of
the affirmation or denial are not propositions; yet these two are
said to be opposed in the same sense as the affirmation and
denial, for in this case also the type of antithesis is the same.
For as the affirmation is opposed to the denial, as in the two