 Leucippus also reportedly accepted the Eleatic Melissus' argument that void is necessary for motion, but took this to be evidence that, since we experience motion, there must be void (DK 67A7). The reason for positing smallest indivisible magnitudes is also reported to be a response to Zeno's argument that, if every magnitude could be divided to infinity, motion would be impossible (DK 29A22). Leucippus is reported to hold that the atoms are always in motion (DK 67A18). Aristotle criticizes him for not offering an account that says not only why a particular atom is moving (because it collided with another) but why there is motion at all. Because the atoms are indestructible and unchangeable, their properties presumably stay the same through all time.