Full Idea
Natural kinds are distinguished from other sorts of things by their associations with essential properties and real essences.
Gist of Idea
Natural kinds are distinguished by resting on essences
Source
Brian Ellis (Scientific Essentialism [2001], 1.02)
Book Reference
Ellis,Brian: 'Scientific Essentialism' [CUP 2007], p.21
A Reaction
I don't think I agree with this. I rest my notion of natural kind on the elementary realising that to know all about this kind you only have to examine one sample of it, as in the Upanishads. The source of such a phenomenon is an open question.
Related Idea
Idea 8153 By knowing one piece of clay or gold, you know all of clay or gold [Anon (Upan)]