Full Idea
That which is means a thing with thisness, a quantity or a quality.
Gist of Idea
Existence requires thisness, as quantity or quality
Source
Aristotle (Metaphysics [c.324 BCE], 1030b12)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.181
A Reaction
I'm happy with a 'quantity' to exist, either in countable or in non-countable form, but not totally convinced that we should treat 'qualities' as fully existing, given their dependence.