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'aquatic', are differentiae of 'animal'; the species of knowledge

are not distinguished by the same differentiae. One species of

knowledge does not differ from another in being 'two-footed'.

But where one genus is subordinate to another, there is nothing to

prevent their having the same differentiae: for the greater class is

predicated of the lesser, so that all the differentiae of the

predicate will be differentiae also of the subject.





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Expressions which are in no way composite signify substance,

quantity, quality, relation, place, time, position, state, action,

or affection. To sketch my meaning roughly, examples of substance

are 'man' or 'the horse', of quantity, such terms as 'two cubits long'

or 'three cubits long', of quality, such attributes as 'white',

'grammatical'. 'Double', 'half', 'greater', fall under the category of

relation; 'in a the market place', 'in the Lyceum', under that of

place; 'yesterday', 'last year', under that of time. 'Lying',

'sitting', are terms indicating position, 'shod', 'armed', state;

'to lance', 'to cauterize', action; 'to be lanced', 'to be

cauterized', affection.

No one of these terms, in and by itself, involves an affirmation; it

is by the combination of such terms that positive or negative

statements arise. For every assertion must, as is admitted, be

either true or false, whereas expressions which are not in any way

composite such as 'man', 'white', 'runs', 'wins', cannot be either

true or false.






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