Full Idea
For a thing to exist necessarily is for it to have an entity-essence whose own entity-essence entails being instantiated.
Gist of Idea
To exist necessarily is to have an essence whose own essence must be instantiated
Source
Michael Jubien (Possibility [2009], 6.4)
Book Reference
Jubien,Michael: 'Possibility' [OUP 2009], p.173
A Reaction
This is the culmination of a lengthy discussion, and is not immediately persuasive. For Jubien the analysis rests on a platonist view of properties, which doesn't help.