The Complete Aristotle (eng.)

living thing of
such a kind as never to be destroyed: and this is equivalent to
saying that it is immortal, so that it is not meant that it is
immortal only at present. Still, if ever it does happen that what
has been rendered according to the definition belongs in the
present only or past, whereas what is meant by the word does not so
belong, then the two could not be the same. So, then, this
commonplace rule ought to be followed, as we have said.
<
    div id="section56" class="section" title="7">
7
    You should look and see also whether the term being defined is
applied in consideration of something other than the definition
rendered. Suppose (e.g.) a definition of ‘justice’ as the ‘ability
to distribute what is equal’. This would not be right, for ‘just’
describes rather the man who chooses, than the man who is able to
distribute what is equal: so that justice could not be an ability
to distribute what is equal: for then also the most just man would
be the man with the most ability to distribute what is equal.
    Moreover, see if the thing admits of degrees, whereas what is
rendered according to the definition does not, or, vice versa, what
is rendered according to the definition admits of degrees while the
thing does not. For either both must admit them or else neither, if
indeed what is rendered according to the definition is the same as
the thing. Moreover, see if, while both of them admit of degrees,
they yet do not both become greater together: e.g. suppose sexual
love to be the desire for intercourse: for he who is more intensely
in love has not a more intense desire for intercourse, so that both
do not become intensified at once: they certainly should, however,
had they been the same thing.
    Moreover, suppose two things to be before you, see if the term
to be defined applies more particularly to the one to which the
content of the definition is less applicable. Take, for instance,
the definition of ‘fire’ as the ‘body that consists of the most
rarefied particles’. For ‘fire’ denotes flame rather than light,
but flame is less the body that consists of the most rarefied
particles than is light: whereas both ought to be more applicable
to the same thing, if they had been the same. Again, see if the one
expression applies alike to both the objects before you, while the
other does not apply to both alike, but more particularly to one of
them.
    Moreover, see if he renders the definition relative to two
things taken separately: thus, the beautiful’ is ‘what is pleasant
to the eyes or to the ears”: or ‘the real’ is ‘what is capable of
being acted upon or of acting’. For then the same thing will be
both beautiful and not beautiful, and likewise will be both real
and not real. For ‘pleasant to the ears’ will be the same as
‘beautiful’, so that ‘not pleasant to the ears’ will be the same as
‘not beautiful’: for of identical things the opposites, too, are
identical, and the opposite of ‘beautiful’ is ‘not beautiful’,
while of ‘pleasant to the ears’ the opposite is not pleasant to the
cars’: clearly, then, ‘not pleasant to the ears’ is the same thing
as ‘not beautiful’. If, therefore, something be pleasant to the
eyes but not to the ears, it will be both beautiful and not
beautiful. In like manner we shall show also that the same thing is
both real and unreal.
    Moreover, of both genera and differentiae and all the other
terms rendered in definitions you should frame definitions in lieu
of the terms, and then see if there be any discrepancy between
them.
<
    div id="section57" class="section" title="8">
8
    If the term defined be relative, either in itself or in respect
of its genus, see whether the definition fails to mention that to
which the term, either in itself or in respect of its genus, is
relative, e.g. if he has defined ‘knowledge’ as an
‘incontrovertible conception’ or ‘wishing’ as ‘painless conation’.
For of everything relative the essence is relative to something
else, seeing that the being of every relative term is identical
with being in a certain relation to something. He ought, therefore,
to have said that knowledge is ‘conception of a knowable’ and that
wishing is ‘conation for a good’. Likewise, also, if he has defined
‘grammar’ as ‘knowledge of letters’: whereas in the definition
there ought to be rendered either the thing to which the term
itself is relative, or that, whatever it is, to which its