The Complete Aristotle (eng.)

properly defined, have a correlative. I
add this condition because, if that to which they are related is
stated as haphazard and not accurately, the two are not found to be
interdependent. Let me state what I mean more clearly. Even in the
case of acknowledged correlatives, and where names exist for each,
there will be no interdependence if one of the two is denoted, not
by that name which expresses the correlative notion, but by one of
irrelevant significance. The term ‘slave,’ if defined as related,
not to a master, but to a man, or a biped, or anything of that
sort, is not reciprocally connected with that in relation to which
it is defined, for the statement is not exact. Further, if one
thing is said to be correlative with another, and the terminology
used is correct, then, though all irrelevant attributes should be
removed, and only that one attribute left in virtue of which it was
correctly stated to be correlative with that other, the stated
correlation will still exist. If the correlative of ‘the slave’ is
said to be ‘the master’, then, though all irrelevant attributes of
the said ‘master’, such as ‘biped’, ‘receptive of knowledge’,
‘human’, should be removed, and the attribute ‘master’ alone left,
the stated correlation existing between him and the slave will
remain the same, for it is of a master that a slave is said to be
the slave. On the other hand, if, of two correlatives, one is not
correctly termed, then, when all other attributes are removed and
that alone is left in virtue of which it was stated to be
correlative, the stated correlation will be found to have
disappeared.
    For suppose the correlative of ‘the slave’ should be said to be
‘the man’, or the correlative of ‘the wing”the bird’; if the
attribute ‘master’ be withdrawn from’ the man’, the correlation
between ‘the man’ and ‘the slave’ will cease to exist, for if the
man is not a master, the slave is not a slave. Similarly, if the
attribute ‘winged’ be withdrawn from ‘the bird’, ‘the wing’ will no
longer be relative; for if the so-called correlative is not winged,
it follows that ‘the wing’ has no correlative.
    Thus it is essential that the correlated terms should be exactly
designated; if there is a name existing, the statement will be
easy; if not, it is doubtless our duty to construct names. When the
terminology is thus correct, it is evident that all correlatives
are interdependent.
    Correlatives are thought to come into existence simultaneously.
This is for the most part true, as in the case of the double and
the half. The existence of the half necessitates the existence of
that of which it is a half. Similarly the existence of a master
necessitates the existence of a slave, and that of a slave implies
that of a master; these are merely instances of a general rule.
Moreover, they cancel one another; for if there is no double it
follows that there is no half, and vice versa; this rule also
applies to all such correlatives. Yet it does not appear to be true
in all cases that correlatives come into existence simultaneously.
The object of knowledge would appear to exist before knowledge
itself, for it is usually the case that we acquire knowledge of
objects already existing; it would be difficult, if not impossible,
to find a branch of knowledge the beginning of the existence of
which was contemporaneous with that of its object.
    Again, while the object of knowledge, if it ceases to exist,
cancels at the same time the knowledge which was its correlative,
the converse of this is not true. It is true that if the object of
knowledge does not exist there can be no knowledge: for there will
no longer be anything to know. Yet it is equally true that, if
knowledge of a certain object does not exist, the object may
nevertheless quite well exist. Thus, in the case of the squaring of
the circle, if indeed that process is an object of knowledge,
though it itself exists as an object of knowledge, yet the
knowledge of it has not yet come into existence. Again, if all
animals ceased to exist, there would be no knowledge, but there
might yet be many objects of knowledge.
    This is likewise the case with regard to perception: for the
object of perception is, it appears, prior to the act of
perception. If the perceptible is annihilated, perception also will
cease to exist; but the annihilation of perception does not cancel
the existence of the perceptible. For perception implies a