ABSTRACT
The topic of substance, essence and accident was often touched on in the first volume of the present work, in discussions of logical form, of method, of perception (including the distinction between primary and secondary qualities, and the perception of the 'coexistence' of qualities) and of innate ideas.1 The notion of substance is almost as pervasive and just as important in the Essay as the notion of an idea, with which it interlocks. Its interpretation there has been no less controversial. The account of Locke's argument offered below is in conflict with what has been the received view, and perhaps is still a common one, that for Locke 'substance' was something to be opposed to all attributes as pure logical subject to all predicates. The latter understanding of substance would make it, of course, unknowable and indescribable in principle. For to have knowledge of something can only be to have knowledge of its attributes, and to describe it must be to ascribe predicates to it.
