Full Idea
Things which are uniform, containing no variety, are always mere abstractions: for instance, time, space, and the other entities of pure mathematics.
Gist of Idea
Wholly uniform things like space and numbers are mere abstractions
Source
Gottfried Leibniz (New Essays on Human Understanding [1704], 2.01)
Book Reference
Leibniz,Gottfried: 'New Essays on Human Understanding', ed/tr. Remnant/Bennett [CUP 1996], p.109
A Reaction
I presume that being 'mere abstractions' denies them ontological status, and makes them creations of thought. If so, I like this idea a lot.