Plotinos: Complete Works, v. 1 In Chronological Order,...

9. It may be objected that it would be impossible to conceive of something without magnitude. The fact is that not everything is identical with quantity. Essence is distinct from quantity; for many other things beside it exist. Consequently no incorporeal nature has any quantity. Matter, therefore, is incorporeal. Besides, even quantity itself is not quantative, which characterizes only what participates in quantity (in general); a further proof that quantity is a form, as an object becomes white by the presence of whiteness; and as that which, in the animal, produces whiteness and the different colors, is not a varied color, but a varied reason; likewise that which produces a quantity is not a definite quantity, but either quantity in itself, or quantity as such, or the reason of quantity. Does quantity, on entering into matter extend matter, so as to give it magnitude? By no means, for matter had not been condensed. Form therefore imparts to matter the magnitude which it did not possess, just as form impresses on matter the quality it lacked.297