definitely that such and such a thing is 'double', he will also
forthwith know definitely that of which it is the double. For if
there is nothing definite of which he knows it to be the double,
he does not know at all that it is double. Again, if he knows
that a thing is more beautiful, it follows necessarily that he
will forthwith definitely know that also than which it is more
beautiful. He will not merely know indefinitely that it is more
beautiful than something which is less beautiful, for this would
be supposition, not knowledge. For if he does not know definitely
that than which it is more beautiful, he can no longer claim to
know definitely that it is more beautiful than something else
which is less beautiful: for it might be that nothing was less
beautiful. It is, therefore, evident that if a man apprehends
some relative thing definitely, he necessarily knows that also
definitely to which it is related.

Now the head, the hand, and such things are substances, and it is
possible to know their essential character definitely, but it
does not necessarily follow that we should know that to which
they are related. It is not possible to know forthwith whose head
or hand is meant. Thus these are not relatives, and, this being
the case, it would be true to say that no substance is relative
in character. It is perhaps a difficult matter, in such cases, to
make a positive statement without more exhaustive examination,
but to have raised questions with regard to details is not
without advantage.

Part 8

By 'quality' I mean that in virtue of which people are said to be