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.