Plutarch, De Stoicorum repugnantiis
Goodwin, Ed.

It is often said by Chrysippus, that there is without the world an infinite vacuum, and that this infinity has neither beginning, middle, nor end. And by this the Stoics chiefly refute that spontaneous motion of the atoms downward, which is taught by Epicurus; there not being in [p. 471] infinity any difference according to which one thing is thought to be above, another below. But in his Fourth Book of Things Possible, having supposed a certain middle place and middle region, he says that the world is situated there. The words are these: ‘Wherefore, if it is to be said of the world that it is corruptible, this seems to want proof; yet nevertheless it rather appears to me to be so. However, its occupation of the place wherein it stands cooperates very much towards its seeming to be incorruptible, because it is in the midst; since if it were thought to be anywhere else, corruption would absolutely take hold of it.’ And again, a little after: ‘For so also in a manner has essence happened eternally to possess the middle place, being immediately from the beginning such as it is; so that both by another manner and through this chance it admits not any corruption, and is therefore eternal.’ These words have one apparent and visible contradiction, to wit, his admitting a certain middle place and middle region in infinity. They have also a second, more obscure indeed, but withal more absurd than this. For thinking that the world would not have remained incorruptible if its situation had happened to have been in any other part of the vacuum, he manifestly appears to have feared lest, the parts of essence moving towards the middle, there should be a dissolution and corruption of the world. Now this he would not have feared, had he not thought that bodies do by nature tend from every place towards the middle, not of essence, but of the region containing essence; of which also he has frequently spoken, as of a thing impossible and contrary to Nature; for that (as he says) there is not in the vacuum any difference by which bodies are drawn rather this way than that way, but the construction of the world is the cause of motion, bodies inclining and being carried from every side to the centre and middle of it. It is sufficient to this purpose, to set down the text out of his [p. 472] Second Book of Motion; for having discoursed, that the world indeed is a perfect body, but that the parts of the world are not perfect, because they have in some sort respect to the whole and are not of themselves; and going forward concerning its motion, as having been framed by Nature to be moved by all its parts towards compaction and cohesion, and not towards dissolution and breaking, he says thus: ‘But the universe thus tending and being moved to the same point, and the parts having the same motion from the nature of the body, it is probable that all bodies have this first motion according to Nature towards the centre of the world,—the world being thus moved as regards itself, and the parts being thus moved as being its parts.’ What then ailed you, good sir (might some one say to him), that you have so far forgotten those words, as to affirm that the world, if it had not casually possessed the middle place, would have been dissoluble and corruptible? For if it is by Nature so framed as always to incline towards the middle, and its parts from every side tend to the same, into what place soever of the vacuum it should have been transposed,—thus containing and (as it were) embracing itself,—it would have remained incorruptible and without danger of breaking. For things that are broken and dissipated suffer this by the separation and dissolution of their parts, every one of them hasting to its own place from that which it had contrary to Nature. But you, being of opinion that, if the world should have been seated in any other place of the vacuum, it would have been wholly liable to corruption, and affirming the same, and therefore asserting a middle in that which naturally can have no middle,— to wit, in that which is infinite,—have indeed dismissed these tensions, coherences, and inclinations, as having nothing available to its preservation, and attributed all the cause of its permanency to the possession of place. And, as if you were ambitious to confute yourself, to the things [p. 473] you have said before you join this also: ‘In whatsoever manner every one of the parts moves, being coherent to the rest, it is agreeable to reason that in the same also the whole should move by itself; yea, though we should, for argument's sake, imagine and suppose it to be in some vacuity of this world; for as, being kept in on every side, it would move towards the middle, so it would continue in the same motion, though by way of disputation we should admit that there were on a sudden a vacuum round about it.’ No part then whatsoever, though encompassed by a vacuum, loses its inclination moving it towards the middle of the world; but the world itself, if chance had not prepared it a place in the middle, would have lost its containing vigor, the parts of its essence being carried some one way, some another.