For as to the inconvenience which some do seem to fear, and in respect of which they confine all the matter within one world, lest, there remaining any thing without, it should disturb the composition of this, by the resistances and jars which it would make against it,—they have no need to dread this. For, there being many worlds, and each of them in particular having one definite and determinate measure and limit of its substance and matter, no part thereof will be without order and good disposition, nothing will remain superfluous or be cast out as an excrement. For the reason which belongeth to each world, being able to rule and govern the matter that is allotted thereto, will not suffer that any thing shall run out of course and order, and rencounter and jumble another world, nor likewise that any thing from another shall justle or disturb it, there being nothing in Nature infinite and inordinate in quantity, nor in motion without reason and order. And if perhaps there be any influence that passes from the one to the other, this is a fraternal communication, whereby they mix themselves together, like the light of the stars and the influence of their temperatures, and whereby they themselves do rejoice in beholding one another with a benign aspect, and give to the Gods (who are good and many in number in every world) an opportunity of knowing and caressing one another. For there is nothing in all this that is impossible, or fabulous, or contrary to reason; though some may think so because of the opinion of Aristotle, who saith that all bodies have their proper and natural places, by which means the earth must on all sides tend to the midst, and the water must rest upon it, serving by its weight for a foundation to the other lighter elements. Were there then many worlds, the earth would be often found above the airy and fiery regions, and as often under them; while air and water would be sometimes in their natural places, and sometimes in others which are their unnatural; which things being impossible, as he thinks, it follows then, there are neither two nor more worlds, but one only, which is this here, consisting of all kinds of elements, disposed according to Nature, agreeably to the diversity of bodies.

But in all this there is more probability than truth. For consider, friend Demetrius; when he saith that some bodies tend towards the midst, which is to say, downwards, the others from the midst, that is, upward, and a third sort move round about the midst, what does he mean by the midst? This cannot be understood in respect of a vacuum, there being no such thing in Nature, as he says himself; and, moreover, those that do allow it say that it can have no middle, no more than beginning and end; for beginning and end are extremities, but that which is infinite, everybody knows, is without an end. But supposing we should be necessitated to admit a middle in a vacuum, it is impossible to comprehend and imagine the difference in the motions of bodies towards it, because there is neither in this vacuum any power attractive of the body, nor in the bodies any inclination or affection to tend on all sides to this middle. And it is no less difficult to imagine that bodies can move of themselves towards an incorporeal place, or receive any motion from it. This middle then must be understood not locally, but corporeally. For this world being a mass and union consisting of different bodies joined together, this diversity of them must beget different motions from one another; which appears in that each of these bodies changing its substance does at the same time change its place. For subtilization and rarefaction dissipate the matter which springeth from the midst and ariseth upwards; whereas, on the contrary, condensation and constipation depress and drive it down towards the middle.