XXV. ‘Again, the chief fear which has led some to use [Sidenote: 424] up the whole of matter on our world, that nothing may be left outside to disturb its coherence by resistance or thrusts, is a needless one. For suppose several worlds, to each of which is apportioned its own being, and matter definitely measured and limited, then nothing will be left outside without place or formation, like an extruded remnant, to put pressure from without. For the law which has control of the matter allotted to each world will not allow anything to be thrust out and wander to strike upon another world, or anything from another to strike its own, because Nature admits neither quantity without limit, nor movement without law and arrangement. [Sidenote: B] Or, even if any stream be drawn off and pass from worlds to other worlds, it must needs be homogeneous and kindly, mingling itself mildly with all, as the stars when they blend their rays. And the worlds themselves must have delight, as they gaze on one another in friendliness, and must also provide for the Gods in each, who are many and good, times of intercourse and common cheerfulness. There is nothing impossible in all this, no fairy tale and no paradox; unless, mark me, the views of Aristotle[168] are to bring it into suspicion on physical grounds. For if each body has its own place, as he says it has, earth must necessarily move towards the centre [Sidenote: C] from every side, and the water rest upon it, underlying the lighter elements because of its weight. If, then, there are many worlds, the result will be that earth is in many places above fire and air, and in many below them; and the same with air and water too, which will be here in natural places, there in unnatural. Which being impossible, as he thinks, there must neither be two worlds nor more than two, but this one only, composed of all matter, and established according to Nature and to the several qualities of matter.