Full Idea
Essence has been conceived either on the model of definition, involving the 'real' as opposed to 'nominal' definitions, or it is elucidated in modal terms, located in de re cases of modal attributions (an object being necessarily a certain way).
Gist of Idea
Essences are either taken as real definitions, or as necessary properties
Source
Kit Fine (Essence and Modality [1994], p. 2)
Book Reference
-: 'Philosophical Perspectives' [-], p.2
A Reaction
[compressed] Fine sets out to defend the definitional view, which derives from Aristotle, his line being that necessity depends on essence, and so cannot be used to define it. I think I agree.