There are three opinions on the matter. One holds that the final limit is the indivisible atom; another that a body is divisible without end; and a third—correct view—that it can be divided only to a determinate point without positing any indivisible atom. The third is the sound position, for maintaining the existence of an atom that cannot be further divided is untenable for many reasons: in every existent thing one part is distinguishable from another. Conversely, to claim an infinite series of divisions within something bounded on all sides is impossible, for the infinite cannot reside inside the finite, nor be confined by it.

Take a body such as water: it can undergo only a finite number of divisions until its parts become exceedingly minute; once they reach that degree of smallness, they change into another substance, so that nothing remains that is still subject to division. It is not therefore divisible ad infinitum; rather, at the point of extreme subtlety it undergoes a transformation and ceases to accept further division in actuality, even though internally one element remains distinguishable from another. Not everything that contains such internal distinction must be actually divisible; the potential for division can weaken until, when the parts become extremely fine, the body cannot remain as it is and is transformed. Any body must possess some magnitude and some quality; when its magnitude becomes too slight to maintain that quality, it will join something else—either undergoing transformation if the other thing is of a different kind, or without transformation if of the same kind. Thus a very small droplet of water, once it becomes exceedingly fine, must either turn into air or dust or merge with another mass of water; otherwise the droplet could not persist on its own. The same applies to all exceedingly minute parts of every body.