— 374 —
Ideas of Substances are real, when they agree with the Existence of Things.       §5. Thirdly, Our complex Ideas of Substances, being made all of
them in reference to Things existing without us, and intended to be
Representations of Substances, as they really are, are no farther
real, than as they are such Combinations of simple Ideas, as are
really united, and co-exist in Things without us. On the contrary,
those are fantastical, which are made up of such Collections of
simple Ideas, as were really never united, never were found together
in any Substance; v.g. a rational Creature, consisting of a Horse’s
Head, joined to a body of humane shape, or such as the Centaurs are
described: Or, a Body, yellow, very malleable, fusible, and fixed;
but lighter than common Water: Or, an uniform, unorganized
Body, consisting as to Sense, all of similar Parts, with Perception
and voluntary Motion joined to it. Whether such Substances, as
these, can possibly exist, or no, ’tis probable we do not know: But
be that as it will, these Ideas of Substances, being made conformable
to no Pattern existing, that we know; and consisting of such
Collections of Ideas, as no Substance ever shewed us united together,
they ought to pass with us for barely imaginary: But much more
are those complex Ideas so, which contain in them any Inconsistency
or Contradiction of their Parts.
Locke Hum II, 30, §5, p. 374