Full Idea
Modes are not nothing but something more than mere nothing; they are therefore 'res' of some kind, not substantial of course, but at least modal.
Gist of Idea
Modes of things exist in some way, without being full-blown substances
Source
Pierre Gassendi (Disquisitions [1644], II.3.4), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 260
Book Reference
Pasnau,Robert: 'Metaphysical Themes 1274-1671' [OUP 2011], p.260
A Reaction
This is the great modern atomist talking pure scholastic metaphysics. He's been reading Suárez. Gassendi seems to accept more than one type of existence.