in Metaphyfics, that which confiftutes the particular nature of each genus or kind, and diftinguifhes it from all others: being nothing but that abstract idea to which this name is affixed, fo that every thing contained in it is effential to that particular kind.

This Mr Locke calls the nominal efence; in contradiftinction to the real efence, or confitution of fubfiances on which this nominal efence depends. Thus the nominal efence of gold is that complex idea the word gold stands for; let it be, for instance, a body, yellow, weighty, malleable, fusible, and fixed: but its real efence is the confitution of its infensible parts, on which thefe qualities and all its other properties depend, which is wholly unknown to us.