Full Idea
The mathematician conducts a study into things in abstraction (after the removal of all perceptible features, such as weight and hardness, leaving only quantity and continuity).
Gist of Idea
Mathematicians study quantity and continuity, and remove the perceptible features of things
Source
Aristotle (Metaphysics [c.324 BCE], 1061a26)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.325
A Reaction
Frege complained that there is nothing left if you remove the perceptible features, but clearly Aristotle is not an empiricist in this passage, and it is doubtful if even Mill can be totally empirical in his account. We have relations of ideas.