Full Idea
If each object has a unique essence or definition, this may be identified with either the class of properties that it essentially has, or with the class of propositions that are true in virtue of what it is.
Gist of Idea
The essence or definition of an essence involves either a class of properties or a class of propositions
Source
Kit Fine (Senses of Essence [1995], §8)
Book Reference
'Modality, Morality and Belief', ed/tr. Sinnott-Armstrong/Raffman/Asher [CUP 1995], p.66
A Reaction
Elsewhere Fine says that it is easier to work with the propositions view, but that the properties (or predicates) view is probably more fundamental. He goes on here to raise the question of whether either view makes the essence unique.