Full Idea
For an Aristotelian not all necessary properties are essential; the essential properties are those that define a thing as what it is.
Gist of Idea
Aristotelians deny that all necessary properties are essential
Source
Robert Pasnau (Metaphysical Themes 1274-1671 [2011], 24.1)
Book Reference
Pasnau,Robert: 'Metaphysical Themes 1274-1671' [OUP 2011], p.551
A Reaction
I take it as basic that whatever is essential is in some way important, whereas necessities can be trivial.