Capítulo 17. Chapter XVII.—Concerning Rest
[3.17.115] In like manner some have doubted about physical rest,[426] say ing that what is in motion is not at rest, but every body i is constantly in motion according to the views of the Dogmatists who assert that Being is in flux[427] and always undergoing effluxes and additions— just as Plato does not even speak of bodies as ‟being” but rather calls them ‟becoming,” and Heracleitus compares the mobility of our matter[428] to the swift current of a river. Therefore no body is at rest.
[3.17.116] What is said to be at rest is, in fact, held to be embraced by the things which surround it, and what is embraced is acted upon; but nothing acted upon exists, since no causal activity exists, as we have shown;[429] therefore nothing is at rest.
Some, too, propound this argument: What is at rest is acted upon; but what is acted upon is in motion; therefore what is said to be at rest is in motion; but if it is in motion, it is not at rest.
[3.17.117] And from this it is evident that neither does the incorporeal admit of being at rest. For if what is at rest is acted upon, and being acted upon is a property, if anything, of bodies and not of incorporeals, no incorporeal can either be acted upon or be at rest; therefore nothing is at rest.
[3.17.118] So much for the subject of rest. And since no one of the things we have mentioned is conceived apart from space or time, we must pass on to consider these; for if one should prove these to be unreal, then, because of them, each of the others also will be unreal. Let us begin with space.