understand, the names of complex ideas that are made up of them. But
when any term stands for a simple idea that a man has never yet had in
his mind, it is impossible by any words to make known its meaning to
him. When any term stands for an idea a man is acquainted with, but is
ignorant that that term is the sign of it, then another name of the
same idea, which he has been accustomed to, may make him understand
its meaning. But in no case whatsoever is any name of any simple idea
capable of a definition.


15. Fourthly, Names of simple Ideas of less doubtful meaning than those
of mixed modes and substances.

Fourthly, But though the names of simple ideas have not the help of
definition to determine their signification, yet that hinders not but
that they are generally less doubtful and uncertain than those of
mixed modes and substances; because they, standing only for one simple
perception, men for the most part easily and perfectly agree in their
signification; and there is little room for mistake and wrangling about
their meaning. He that knows once that whiteness is the name of that
colour he has observed in snow or milk, will not be apt to misapply that
word, as long as he retains that idea; which when he has quite lost, he
is not apt to mistake the meaning of it, but perceives he understands it
not. There is neither a multiplicity of simple ideas to be put together,
which makes the doubtfulness in the names of mixed modes; nor a
supposed, but an unknown, real essence, with properties depending
thereon, the precise number whereof is also unknown, which makes the
difficulty in the names of substances. But, on the contrary, in simple
ideas the whole signification of the name is known at once, and consists
not of parts, whereof more or less being put in, the idea may be varied,