 Despite the counterintuitive nature of al-Naẓẓām’s suggestion, he argued that even the atomists had to posit leaps as well. He had one imagine the rotation of a millstone. Now in a single rotation an atom at the outer edge of the wheel would traverse a distance equal to the circumference of the wheel, whereas an atom at the hub would traverse a shorter distance equal to the circumference of the hub. Since the atom at the outer edge is traversing a greater distance in an equal time as the atom at the hub, the atom at the outer edge must be moving faster than the atom at the hub. Al-Naẓẓām next observed that there is only one of two ways to explain this phenomenon: either the atom at the outer edge leaps over some of the intervening atomic cells, or the atom at the hub rests at some of the atomic cells for a few moments while the atom at the outer edge catches up. The preferred atomist solution to differences in velocity was to posit that slower moving objects have a greater number of intervallic rests than faster moving objects; however, al-Naẓẓā]m disallowed this solution with respect to the rotating millstone on the grounds that in that case the millstone would fragment as certain atoms rest while others keep moving. In other words, some atoms that at the beginning of the motion had been next to other atoms would have moved away from each other as the ones nearer the rim kept moving in order to cover the greater distance and the ones nearer the hub rested in order to cover only their respective distance, and so by the atom’s moving away from each other, the millstone as a whole would fragment and break up. Yet, argued al-Naẓẓām, it is directly observable that the stone does not fragment, and thus even the atomists must be committed to leaps. (For a discussion of al-Naẓẓām’s theory of leaps and possible historical sources available to him see Chase (2019).)