Full Idea
That which is necessary for something does not constitute its essence. Air is necessary for our life, but our life is something other than air.
Gist of Idea
A necessary feature (such as air for humans) is not therefore part of the essence
Source
Gottfried Leibniz (Letters to Queen Charlotte [1702], 1702)
Book Reference
Leibniz,Gottfried: 'Philosophical Essays', ed/tr. Arlew,R /Garber,D [Hackett 1989], p.191
A Reaction
Bravo. Why can't modern philosophers hang on to this distinction? They seem to think that because they don't believe in traditional essences they can purloin the word for something else. Same with the word 'abstraction'.