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therefore, and see if in the case of any of its species the genus be
imparted only in a certain respect; e.g. if 'animal' has been
described as an 'object of perception' or of 'sight'. For an animal is
an object of perception or of sight in a particular respect only; for
it is in respect of its body that it is perceived and seen, not in
respect of its soul, so that-'object of sight' and 'object of
perception' could not be the genus of 'animal'.
Sometimes also people place the whole inside the part without
detection, defining (e.g.) 'animal' as an 'animate body'; whereas the
part is not predicated in any sense of the whole, so that 'body' could
not be the genus of animal, seeing that it is a part.
See also if he has put anything that is blameworthy or objectionable
into the class 'capacity' or 'capable', e.g. by defining a 'sophist'
or a 'slanderer', or a 'thief' as 'one who is capable of secretly
thieving other people's property'. For none of the aforesaid
characters is so called because he is 'capable' in one of these
respects: for even God and the good man are capable of doing bad
things, but that is not their character: for it is always in respect
of their choice that bad men are so called. Moreover, a capacity is
always a desirable thing: for even the capacities for doing bad things
are desirable, and therefore it is we say that even God and the good
man possess them; for they are capable (we say) of doing evil. So then
'capacity' can never be the genus of anything blameworthy. Else, the
result will be that what is blameworthy is sometimes desirable: for
there will be a certain form of capacity that is blameworthy.
Also, see if he has put anything that is precious or desirable for its
own sake into the class 'capacity' or 'capable' or 'productive' of
anything. For capacity, and what is capable or productive of anything,
is always desirable for the sake of something else.
Or see if he has put anything that exists in two genera or more into
one of them only. For some things it is impossible to place in a
single genus, e.g. the 'cheat' and the 'slanderer': for neither he who
has the will without the capacity, nor he who has the capacity without
the will, is a slanderer or cheat, but he who has both of them. Hence
he must be put not into one genus, but into both the aforesaid genera.
Moreover, people sometimes in converse order render genus as
differentia, and differentia as genus, defining (e.g.) astonishment as
'excess of wonderment' and conviction as 'vehemence of conception'.
For neither 'excess' nor 'vehemence' is the genus, but the
differentia: for astonishment is usually taken to be an 'excessive
wonderment', and conviction to be a 'vehement conception', so that
'wonderment' and 'conception' are the genus, while 'excess' and
'vehemence' are the differentia. Moreover, if any one renders 'excess'
and 'vehemence' as genera, then inanimate things will be convinced and
astonished. For 'vehemence' and 'excess' of a thing are found in a
thing which is thus vehement and in excess. If, therefore,
astonishment be excess of wonderment the astonishment will be found in
the wonderment, so that 'wonderment' will be astonished! Likewise,
also, conviction will be found in the conception, if it be 'vehemence
of conception', so that the conception will be convinced. Moreover, a
man who renders an answer in this style will in consequence find
himself calling vehemence vehement and excess excessive: for there is
such a thing as a vehement conviction: if then conviction be
'vehemence', there would be a 'vehement vehemence'. Likewise, also,
there is such a thing as excessive astonishment: if then astonishment
be an excess, there would be an 'excessive excess'. Whereas neither of
these things is generally believed, any more than that knowledge is a
knower or motion a moving thing.
Sometimes, too, people make the bad mistake of putting an affection
into that which is affected, as its genus, e.g. those who say that
immortality is everlasting life: for immortality seems to be a certain
affection or accidental feature of life. That this saying is true
would appear clear if any one were to admit that a man can pass from
being mortal and become immortal: for no one will assert that he takes