Full Idea
A 'genus' is that which is predicated in the category of essence of several things which differ in kind.
Gist of Idea
'Genus' is part of the essence shared among several things
Source
Aristotle (Topics [c.331 BCE], 102a32)
Book Reference
Aristotle: 'Posterior Analytics and Topica', ed/tr. Tredennick,H/Forster,ES [Harvard 1960], p.283
A Reaction
Hence a genus is likely to be expressed by a universal, a one-over-many. A particular will be a highly individual collection of various genera, but what ensures the uniqueness of each thing, if they are indiscernible?