relative, as seems to be the case, or whether exception is to be
made in the case of certain secondary substances. With regard to
primary substances, it is quite true that there is no such
possibility, for neither wholes nor parts of primary substances are
relative. The individual man or ox is not defined with reference to
something external. Similarly with the parts: a particular hand or
head is not defined as a particular hand or head of a particular
person, but as the hand or head of a particular person. It is true
also, for the most part at least, in the case of secondary substances;
the species 'man' and the species 'ox' are not defined with
reference to anything outside themselves. Wood, again, is only
relative in so far as it is some one's property, not in so far as it
is wood. It is plain, then, that in the cases mentioned substance is
not relative. But with regard to some secondary substances there is
a difference of opinion; thus, such terms as 'head' and 'hand' are
defined with reference to that of which the things indicated are a
part, and so it comes about that these appear to have a relative
character. Indeed, if our definition of that which is relative was
complete, it is very difficult, if not impossible, to prove that no
substance is relative. If, however, our definition was not complete,
if those things only are properly called relative in the case of which
relation to an external object is a necessary condition of
existence, perhaps some explanation of the dilemma may be found.

  The former definition does indeed apply to all relatives, but the
fact that a thing is explained with reference to something else does
not make it essentially relative.

  From this it is plain that, if a man definitely apprehends a
relative thing, he will also definitely apprehend that to which it
is relative. Indeed this is self-evident: for if a man knows that some
particular thing is relative, assuming that we call that a relative in
the case of which relation to something is a necessary condition of
existence, he knows that also to which it is related. For if he does
not know at all that to which it is related, he will not know
whether or not it is relative. This is clear, moreover, in
particular instances. If a man knows 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.

                                 8

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

  Quality is a term that is used in many senses. One sort of quality
let us call 'habit' or 'disposition'. Habit differs from disposition
in being more lasting and more firmly established. The various kinds
of knowledge and of virtue are habits, for knowledge, even when
acquired only in a moderate degree, is, it is agreed, abiding in its
character and difficult to displace, unless some great mental upheaval
takes place, through disease or any such cause. The virtues, also,
such as justice, self-restraint, and so on, are not easily dislodged
or dismissed, so as to give place to vice.

  By a disposition, on the other hand, we mean a condition that is
easily changed and quickly gives place to its opposite. Thus, heat,
cold, disease, health, and so on are dispositions. For a man is
disposed in one way or another with reference to these, but quickly
changes, becoming cold instead of warm, ill instead of well. So it
is with all other dispositions also, unless through lapse of time a
disposition has itself become inveterate and almost impossible to
dislodge: in which case we should perhaps go so far as to call it a
habit.

  It is evident that men incline to call those conditions habits which
are of a more or less permanent type and difficult to displace; for
those who are not retentive of knowledge, but volatile, are not said
to have such and such a 'habit' as regards knowledge, yet they are
disposed, we may say, either better or worse, towards knowledge.
Thus habit differs from disposition in this, that while the latter
in ephemeral, the former is permanent and difficult to alter.

  Habits are at the same time dispositions, but dispositions are not
necessarily habits. For those who have some specific habit may be said
also, in virtue of that habit, to be thus or thus disposed; but
those who are disposed in some specific way have not in all cases
the corresponding habit.