The Complete Aristotle (eng.)

which differ most are contrary (for the complete
difference is the greatest difference between species of the same
genus); and (3) the things in the same receptive material which
differ most are contrary (for the matter is the same for
contraries); and (4) of the things which fall under the same
faculty the most different are contrary (for one science deals with
one class of things, and in these the complete difference is the
greatest).
    The primary contrariety is that between positive state and
privation-not every privation, however (for ‘privation’ has several
meanings), but that which is complete. And the other contraries
must be called so with reference to these, some because they
possess these, others because they produce or tend to produce them,
others because they are acquisitions or losses of these or of other
contraries. Now if the kinds of opposition are contradiction and
privation and contrariety and relation, and of these the first is
contradiction, and contradiction admits of no intermediate, while
contraries admit of one, clearly contradiction and contrariety are
not the same. But privation is a kind of contradiction; for what
suffers privation, either in general or in some determinate way,
either that which is quite incapable of having some attribute or
that which, being of such a nature as to have it, has it not; here
we have already a variety of meanings, which have been
distinguished elsewhere. Privation, therefore, is a contradiction
or incapacity which is determinate or taken along with the
receptive material. This is the reason why, while contradiction
does not admit of an intermediate, privation sometimes does; for
everything is equal or not equal, but not everything is equal or
unequal, or if it is, it is only within the sphere of that which is
receptive of equality. If, then, the comings-to-be which happen to
the matter start from the contraries, and proceed either from the
form and the possession of the form or from a privation of the form
or shape, clearly all contrariety must be privation, but presumably
not all privation is contrariety (the reason being that that has
suffered privation may have suffered it in several ways); for it is
only the extremes from which changes proceed that are
contraries.
    And this is obvious also by induction. For every contrariety
involves, as one of its terms, a privation, but not all cases are
alike; inequality is the privation of equality and unlikeness of
likeness, and on the other hand vice is the privation of virtue.
But the cases differ in a way already described; in one case we
mean simply that the thing has suffered privation, in another case
that it has done so either at a certain time or in a certain part
(e.g. at a certain age or in the dominant part), or throughout.
This is why in some cases there is a mean (there are men who are
neither good nor bad), and in others there is not (a number must be
either odd or even). Further, some contraries have their subject
defined, others have not. Therefore it is evident that one of the
contraries is always privative; but it is enough if this is true of
the first-i.e. the generic-contraries, e.g. the one and the many;
for the others can be reduced to these.
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5
    Since one thing has one contrary, we might raise the question
how the one is opposed to the many, and the equal to the great and
the small. For if we used the word ‘whether’ only in an antithesis
such as ‘whether it is white or black’, or ‘whether it is white or
not white’ (we do not ask ‘whether it is a man or white’), unless
we are proceeding on a prior assumption and asking something such
as ‘whether it was Cleon or Socrates that came’ as this is not a
necessary disjunction in any class of things; yet even this is an
extension from the case of opposites; for opposites alone cannot be
present together; and we assume this incompatibility here too in
asking which of the two came; for if they might both have come, the
question would have been absurd; but if they might, even so this
falls just as much into an antithesis, that of the ‘one or many’,
i.e. ‘whether both came or one of the two’:-if, then, the question
‘whether’ is always concerned with opposites, and we can ask
‘whether it is greater or less or equal’, what is the opposition of
the equal to the other two? It is not contrary either to one alone
or to both; for why should it be contrary to the greater