— 421 —
Thirdly, Names of simple Ideas undefinable.       §4. Thirdly, The Names of simple Ideas are not capable of any
definitions; the Names of all complex Ideas are. It has not, that I
know, hitherto been taken notice of by any Body, what Words are,
and what are not capable of being defined: the want whereof is (as I
am apt to think) not seldom the occasion of great wrangling, and
obscurity in Men’s Discourses, whilst some demand definitions of
Terms, that cannot be defined; and others think, they ought to
rest satisfied, in an Explication made by a more general Word, and
its Restriction, (or to speak in Terms of Art by a Genus and
Difference,) when even after such Definition made according to
rule, those who hear it, have often no more a clear Conception of
the meaning of the Word, than they had before. This at least, I
think, that the shewing what Words are, and what are not capable
of Definitions, and wherein consists a good Definition, is not wholly
besides our present purpose; and perhaps, will afford so much
Light to the Nature of these Signs, and our Ideas, as to deserve a
more particular Consideration.
Locke Hum III, 4, §4, p. 421