Des Cartes maintained that thought was the essence of the mind; not this thought or that thought, but thought in general.This seems to be absolutely unintelligible, since every thing, that exists, is particular: And therefore it must be our several particular perceptions, that compose the mind. I say, compose the mind, not belong to it. The mind is not a substance, in which the perceptions inhere. That notion is as unintelligible as the Cartesian, that thought or perception in general is the essence of the mind. We have no idea of substance of any kind, since we have no idea but what is derived from some impression, and we have no impression of any substance either material or spiritual. We know nothing but particular qualities and perceptions. As our idea of any body, a peach, for instance, is only that of a particular taste, colour, figure, size, consistence, &c. So our idea of any mind is only that of particular perceptions, without the notion of any thing we call substance, either simple or compound.