XXVI. ‘However, all this is more plausible than true. Look at it in this way,’ I went on, ‘dear Demetrius: when [Sidenote: D] he says that some bodies move downward towards the middle, others upwards from the middle, others around the middle, with reference to what does he take the middle? Not to the void surely, for on his view there is none. But in the view of those who allow a void, it has no middle, just as it has no first or last, for these are limits, but the infinite has no limits. Or if a man were to force himself, by sheer thinking, to conceive any middle point in an infinite void, what is the resulting difference in the movements of the different bodies towards it? Bodies have no force in the void, nor yet have bodies any choice or impulse to make them aim at the middle and tend towards it from all sides. Besides, where there are bodies with [Sidenote: E] no soul, and a place which is incorporeal and without difference of parts, it is as impossible to conceive of any movement towards it arising out of themselves, as of any attraction upon them arising out of it. It remains that the middle is spoken of not in a local sense but in a corporeal. For granted that this world has unity of structure with many dissimilar elements, the different parts have necessarily different movements towards different objects. This is clear from the consideration [Sidenote: F] that different elements, where their substance is transferred, change their places at the same time; rarefaction distributes in a circular movement the matter raised upwards from the middle; consolidation and condensation press matter downward towards the middle and force it together.