— 380 —
Ideas of Substances, as Collections of their Qualities, are all inadequate.       §8. Secondly, Those who, neglecting that useless Supposition of
unknown real Essences, whereby they are distinguished, endeavour
to copy the Substances, that exist in the World, by putting
— 381 —
together the Ideas of those sensible Qualities, which are found co-
existing in them, though they come much nearer a likeness of
them, than those who imagine, they know not what real specifick
Essences: yet they arrive not at perfectly adequate Ideas of those
Substances, they would thus copy into their Minds: nor do those
Copies, exactly, and fully, contain all that is to be found in their
Archetypes. Because those Qualities, and Powers of Substances,
whereof we make their complex Ideas, are so many and various, that
no Man’s complex Idea contains them all. That our abstract Ideas of
Substances, do not contain in them all the simple Ideas, that are
united in the Things themselves, is evident, in that Men do rarely
put into their complex Idea of any Substance, all the simple Ideas
they do know to exist in it. Because endeavouring to make the
signification of their specifick Names as clear, and as little cumber-
some as they can, they make their specifick Ideas of the sorts of
Substances, for the most part, of a few of those simple Ideas which
are to be found in them: But these having no original precedency, or
right to be put in, and make the specifick Idea, more than others
that are left out, ’tis plain, that both these ways, our Ideas of
Substances are deficient, and inadequate. The simple Ideas whereof we
make our complex ones of Substances, are all of them (bating only
the Figure and Bulk of some sorts) Powers; which being Relations to
other Substances, we can never be sure that we know all the Powers,
that are in any one Body, till we have tried what Changes it is fitted to
give to, or receive from other Substances, in their several ways of
application: which being impossible to be tried upon any one Body,
much less upon all, it is impossible we should have adequate Ideas
of any Substance, made up of a Collection of all its Properties.
Locke Hum II, 31, §8, pp. 380-381