  A reductio ad absurdum argument reported by Aristotle suggests that the atomists argued from the assumption that, if a magnitude is infinitely divisible, nothing prevents it actually having been divided at every point.  The atomist then asks what would remain: if the answer is some extended particles, such as dust, then the hypothesized division has not yet been completed.  If the answer is nothing or points, then the question is how an extended magnitude could be composed from what does not have extension (DK 68A48b, 123).