minately that one of the two contraries, not one or the
other, should be present in the subject; for fire cannot be cold, or
snow black. Thus, it is not the case here that one of the two must
needs be present in every subject receptive of these qualities, but
only in that subject of which the one forms a constitutive property.
Moreover, in such cases it is one member of the pair determinately, and
not either the one or the other, which must be present.

In the case of 'positives' and 'privatives', on the other hand, neither
of the aforesaid statements holds good. For it is not necessary that a
subject receptive of the qualities should always have either the one or
the other; that which has not yet advanced to the state when sight is
natural is not said either to be blind or to see. Thus 'positives' and
'privatives' do not belong to that class of contraries which consists
of those which have no intermediate. On the other hand, they do not
belong either to that class which consists of contraries which have an
intermediate. For under certain conditions it is necessary that either
the one or the other should form part of the constitution of every
appropriate subject. For when a thing has reached the stage when it is
by nature capable of sight, it will be said either to see or to be
blind, and that in an indeterminate sense, signifying that the capacity
may be either present or absent; for it is not necessary either that it
should see or that it should be blind, but that it should be either in
the one state or in the other. Yet in the case of those contraries
which have an intermediate we found that it was never necessary that
either the one or the other should be present in every appropriate
subject, but only that in certain subjects one of the pair should be
present, and that in a determinate sense. It is, therefore, plain that
'positives' and 'privatives' are not opposed each to each in either of
the senses in which contraries are opposed.

Again, in the case of contraries, it is possible that there should be
changes from either into the other, while the subject retains its
identity, unless indeed one of the contraries is a constitutive
property of that subject, as heat is of fire. For it is possible that
that that which is healthy should become diseased, that which is white,
black, that which is cold, hot, that which is good, bad, that which is
bad, good. The bad man, if he is being brought into a better way of
life and