and Verbs. And his
subdivisions of these parts are still followed in our grammars. But
really it is not the grammatical function that he attends to, but
the signification: and looking further at the examples, we see what
differences of signification he had in his mind. It is differences
relative to a concrete individual, differences in the words applied to
him according as they signify the substance of him or his attributes,
permanent or temporary.

Take any concrete thing, Socrates, this book, this table. It must
be some kind of a thing, a man, a book. It must have some size
or quantity, six feet high, three inches broad. It must have some
quality, white, learned, hard. It must have relations with other
things, half this, double that, the son of a father. It must be
somewhere, at some time, in some attitude, with some "havings,"
appendages, appurtenances, or belongings, doing something, or having
something done to it. Can you conceive any name (simple or composite)
applicable to any object of perception, whose signification does not
fall into one or other of these classes? If you cannot, the categories
are justified as an exhaustive division of significations. They are
a complete list of the most general resemblances among individual
things, in other words, of the _summa genera_, the _genera
generalissima_ of predicates concerning this, that or the other
concrete individual. No individual thing is _sui generis_: everything
is like other things: the categories are the most general likenesses.

The categories are exhaustive, but do they fulfil another requisite of
a good division--are they mutually exclusive? Aristotle himself
raised this question, and some of his answers to difficulties are
instructive. Particularly his discussion of the distinction between
Second Substances or Essences and Qualities. Here he approximates to
the modern doctrine of the distinction between Substance and Attribute
as set forth in our quotation from Mansel at p. 110. Aristotle's
Second Essences ([Greek: deuterai ousiai]) are common nouns or general
names, Species and Genera, _man_, _horse_, _animal_, as distinguished
from Singular names, _this man_, _this horse_, which he calls First
Substances ([Greek: protai ousiai]), essences _par excellence_, to
which real existence in the highest sense is attributed. Common nouns
are put in the First Category because they are predicated in answer to
the question, What is this? But he raises the diff