Full Idea
Natural kinds are realistic scientific entities that are differentiated by nature itself rather than by our human attempts at classification.
Gist of Idea
Natural kinds are what are differentiated by nature, and not just by us
Source
Eric R. Scerri (The Periodic Table [2007], Intro 'Evol')
Book Reference
Scerri,Eric R.: 'The Periodic Table' [OUP 2007], p.-1