Full Idea
No differentia indicates the essence [ti estin], but rather some quality, such as 'pedestrian' or 'biped'.
Gist of Idea
The differentia indicate the qualities, but not the essence
Source
Aristotle (Topics [c.331 BCE], 122b17)
Book Reference
Aristotle: 'Posterior Analytics and Topica', ed/tr. Tredennick,H/Forster,ES [Harvard 1960], p.435
A Reaction
We must disentangle this, since essence is what is definable, and definition seems to give us the essence, and yet it appears that definition only requires genus and differentia. Differentiae seem to be both generic and fine-grained. See Idea 12280!
Related Idea
Idea 12280 Genus gives the essence better than the differentiae do [Aristotle]