Full Idea
Fine's view is that the notion of an essential property of a thing should be bound up with the notion of what it is to be that thing (unlike, for example, Socrates being such that there are infinitely many primes).
Gist of Idea
An essential property of something must be bound up with what it is to be that thing
Source
report of Kit Fine (Essence and Modality [1994]) by Adolph Rami - Essential vs Accidental Properties §2
Book Reference
-: 'Philosophical Perspectives' [-], p.5
A Reaction
I would think that Fine is so obviously right that it was hardly worth saying, but philosophers are a funny lot, and are quite likely to claim that features of prime numbers are part of the essence of a long-dead philosopher.