5. Complex Ideas of Substances are real, when they agree with the existence of Things.
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 further 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 human 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, it is 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 showed 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.