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.
