use, is not
so certainly known. And however we are apt to think we well enough know
what is meant by GOLD or IRON; yet the precise complex idea others make
them the signs of is not so certain: and I believe it is very seldom
that, in speaker and hearer, they stand for exactly the same collection.
Which must needs produce mistakes and disputes, when they are made use
of in discourses, wherein men have to do with universal propositions,
and would settle in their minds universal truths, and consider the
consequences that follow from them.

19. And next to them, simple Modes.

By the same rule, the names of SIMPLE MODES are, next to those of simple
ideas, least liable to doubt and uncertainty; especially those of figure
and number, of which men have so clear and distinct ideas. Who ever that
had a mind to understand them mistook the ordinary meaning of SEVEN, or
a TRIANGLE? And in general the least compounded ideas in every kind have
the least dubious names.

20. The most doubtful are the Names of very compounded mixed Modes and
Substances.

Mixed modes, therefore, that are made up but of a few and obvious simple
ideas, have usually names of no very uncertain signification. But the
names of mixed modes, which comprehend a great number of simple ideas,
are commonly of a very doubtful and undetermined meaning, as has been
shown. The names of substances, being annexed to ideas that are neither
the real essences, nor exact representations of the patterns they are
referred to, are liable to yet greater imperfection and uncertainty,
especially when we come to a philosophical use of them.

21. Why this Imperfection charged upon Words.

The great disorder that happens in our names of substances, proceeding,
for the most part, from our want of knowledge, and inability to
penetrate into their real constitutions, it may probably be wondered
why I charge this as an imperfection rather upon our words than
understandings. This exception has so much appearance of justice, that I
think myself obliged to give a reason why I have followed this method.
I must confess, then, that, when I first began this Discourse of the
Understanding, and a good while after, I had not the least thought that
any consideration of words was at all necessary to it. But when, having
passed over the original and composition of our ideas, I began to
examine the extent and certainty of our knowledge, I found it had so
near a connexion with words, that,