Full Idea
The notion of essence makes sense in context. Relative to a particular enquiry, some predicates may play a more basic role than others, or may apply more fixedly; and these may be treated as essential.
Gist of Idea
Essences can make sense in a particular context or enquiry, as the most basic predicates
Source
Willard Quine (Intensions Revisited [1977], p.121)
Book Reference
Quine,Willard: 'Theories and Things' [Harvard 1981], p.121
A Reaction
Quine has got a bad press on essentialism, and on modal logic, but I take this point seriously. If you give something a fixed identity by means of essence in some context, you can then go ahead and apply possible world reasoning in that context.
Related Idea
Idea 8483 Necessity is relative to context; it is what is assumed in an inquiry [Quine]