tion of another term do not appear to predicate anything
concerning the substance of a subject. For instance, master and
slave[23] are relative terms; let us see whether either of them are
predicates of substance. If you suppress the term slave,[24] you
simultaneously suppress the term master. On the other hand, though you
suppress the term whiteness, you do not suppress some white thing,[25]
though, of course, if the particular whiteness inhere as an accident in
the thing, the thing disappears as soon as you suppress the accidental
quality whiteness. But in the case of master, if you suppress the term
slave, the term master disappears. But slave is not an accidental
quality of master, as whiteness is of a white thing; it denotes the
power which the master has over the slave. Now since the power goes when
the slave is removed, it is plain that power is no accident to the
substance of master, but is an adventitious augmentation arising from
the possession of slaves.

It cannot therefore be affirmed that a category of relation increases,
decreases, or alters in any way the substance of the thing to which it
is applied. The category of relation, then, has nothing to do with the
essence of the subject; it simply denotes a condition of relativity, and
that not necessarily to something else, but sometimes to the subject
itself. For suppose a man standing. If I go up to him on my right and
stand beside him, he will be left, in relation to me, not because he is
left in himself, but because I have come up to him on my right. Again,
if I come up to him on my left, he becomes right in relation to me, not
because he is right in himself, as he may be white or long, but because
he is right in virtue of my approach. What he is depends entirely on me,
and not in the least on the essence of his being.

Accordingly those predicates which do not denote the essential nature of
a thing cannot alter, change, or disturb its nature in any way.
Wherefore if Father and Son are predicates of relation, and, as we have
said, have no other difference but that of relation, and if relation is
not asserted of its subject as though it were the subject itself and its
substantial quality, it will effect no real difference in its subject,
but, in a phrase which aims at interpreting what we can hardly
understand, a difference of persons. For it is a canon of absolute truth
that distinctio