Full Idea
Nor indeed can we rank and sort things, and consequently (which is the end of sorting) denominate them by their real essences, because we know them not.
Gist of Idea
We can't categorise things by their real essences, because these are unknown
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 3.06.09)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.444
A Reaction
Hence he says we categorise by the nominal essence, which is the ideas we have formed from our experiences of things. If we now have experts who have mastered some real essences, Locke is wrong, if we submit to the expert categories.