Full Idea
Locke was more interested in 'nominal essences'. ...The abstract idea of various particular substances that resemble each other ..determines a sort or a species, the 'nominal essence', for "everything contained in that idea is essential to that sort".
Gist of Idea
'Nominal essence' is everything contained in the idea of a particular sort of thing
Source
report of John Locke (Essay Conc Human Understanding (2nd Ed) [1694]) by Irving M. Copi - Essence and Accident p.712
Book Reference
-: 'Journal of Philosophy' [-], p.712
A Reaction
[He refers us to Locke 'Essay' 3.3, and others] This seems to be the sortals espoused by Wiggins, so is he more of a Lockean than an Aristotelian? He's a slippery fish. Knowing the sort is said by Locke to be the key to knowledge.