Expansion and duration have this further agreement, that, though they are both considered by us as having parts, yet their parts are not separable one from another, no not even in thought: though the parts of bodies from whence we take our of the one; and the parts of motion, or rather the succession of ideas in our minds, from whence we take the of the other, may be interrupted and separated; as the one is often by rest, and the other is by sleep, which we call rest too.