signification of the name of any substance? All which together, seldom
or never fail to produce that various and doubtful signification in
the names of substances, which causes such uncertainty, disputes, or
mistakes, when we come to a philosophical use of them.


15. With this imperfection, they may serve for civil, but not well for
philosophical Use.

It is true, as to civil and common conversation, the general names of
substances, regulated in their ordinary signification by some obvious
qualities, (as by the shape and figure in things of known seminal
propagation, and in other substances, for the most part by colour,
joined with some other sensible qualities,) do well enough to design the
things men would be understood to speak of: and so they usually
conceive well enough the substances meant by the word gold or apple, to
distinguish the one from the other. But in PHILOSOPHICAL inquiries and
debates, where general truths are to be established, and consequences
drawn from positions laid down, there the precise signification of the
names of substances will be found not only not to be well established
but also very hard to be so. For example: he that shall make
malleability, or a certain degree of fixedness, a part of his complex
idea of gold, may make propositions concerning gold, and draw
consequences from them, that will truly and clearly follow from gold,
taken in such a signification: but yet such as another man can never
be forced to admit, nor be convinced of their truth, who makes not
malleableness, or the same degree of fixedness, part of that complex
idea that the name gold, in his use of it, stands for.