0. Why the Genus is ordinarily made Use of in Definitions.

This may show us the reason why, in the defining of words, which is
nothing but declaring their signification, we make use of the GENUS, or
next general word that comprehends it. Which is not out of necessity,
but only to save the labour of enumerating the several simple ideas
which the next general word or GENUS stands for; or, perhaps, sometimes
the shame of not being able to do it. But though defining by GENUS and
DIFFERENTIA (I crave leave to use these terms of art, though originally
Latin, since they most properly suit those notions they are applied to),
I say, though defining by the GENUS be the shortest way, yet I think it
may be doubted whether it be the best. This I am sure, it is not the
only, and so not absolutely necessary. For, definition being nothing but
making another understand by words what idea the term defined stands
for, a definition is best made by enumerating those simple ideas that
are combined in the signification of the term defined: and if, instead
of such an enumeration, men have accustomed themselves to use the
next general term, it has not been out of necessity, or for greater
clearness, but for quickness and dispatch sake. For I think that, to one
who desired to know what idea the word MAN stood for; if it should be
said, that man was a solid extended substance, having life, sense,
spontaneous motion, and the faculty of reasoning, I doubt not but the
meaning of the term man would be as well understood, and the idea it
stands for be at least as clearly made known, as when it is defined
to be a rational animal: which, by the several definitions of ANIMAL,
VIVENS, and CORPUS, resolves itself into those enumerated ideas. I have,
in explaining the term MAN, followed here the ordinary definition of
the schools; which, though perhaps not the most, exact, yet serves well
enough to my present purpose. And one may, in this instance, see what
gave occasion to the rule, that a definition must consist of GENUS and
DIFFERENTIA; and it suffices to show us the little necessity there is
of such a rule, or advantage in the strict observing of it. For,
definitions, as has been said, being only the explaining of one word
by several others, so that the meaning or idea it stands for may be
certainly known; languages are not always so made according to the rules
of logic, that every term can have its signification exactly and clearly
expressed by two oth