§4.9#1Εἰσὶν δέ τινες οἳ διὰ τοῦ μανοῦ καὶ πυκνοῦ οἴονται φανερὸν εἶναι ὅτι ἔστι κενόν.
And there are some who think it is clear that there is a void through the rare and the dense.
εἰ μὲν γὰρ μὴ ἔστι μανὸν καὶ πυκνόν, οὐδὲ συνιέναι καὶ πιλεῖσθαι οἷόν τε· εἰ δὲ τοῦτο μὴ εἴη, ἢ ὅλως κίνησις οὐκ ἔσται, ἢ κυμανεῖ τὸ ὅλον, ὥσπερ ἔφη Ξοῦθος, ἢ εἰς ἴσον ἀεὶ δεῖ μεταβάλλειν ἀέρα καὶ ὕδωρ (λέγω δὲ οἷον εἰ ἐξ ὕδατος κυάθου γέγονεν ἀήρ, ἅμα ἐξ ἴσου ἀέρος ὕδωρ τοσοῦτον γεγενῆσθαι), ἢ κενὸν εἶναι ἐξ ἀνάγκης· συμπιλεῖσθαι γὰρ καὶ ἐπεκτείνεσθαι οὐκ ἐνδέχεται ἄλλως.
For if there is no rare and dense, it is not possible either to come together and be compressed; and if this should not be, either there will be no motion at all, or the whole will bulge (wave), just as Xuthus said, or air and water must always change into equal amounts (I mean, for example, if from a cup of water air has been generated, at the same time from an equal amount of air so much water must have been generated), or there must of necessity be a void; for to be compressed and to be expanded is not otherwise possible.
εἰ μὲν οὖν τὸ μανὸν λέγουσι τὸ πολλὰ κενὰ κεχωρισμένα ἔχον, φανερὸν ὡς εἰ μηδὲ κενὸν ἐνδέχεται εἶναι χωριστὸν ὥσπερ μηδὲ τόπον ἔχοντα διάστημα αὑτοῦ, οὐδὲ μανὸν οὕτως·
If then by the rare they mean that which has many separated voids, it is clear that if it is not possible for there to be a separated void, just as there is no place having an interval of itself, so too there is no rare in this way.
εἰ δὲ μὴ χωριστόν, ἀλλʼ ὅμως ἐνεῖναί τι κενόν, ἦττον μὲν ἀδύνατον, συμβαίνει δὲ πρῶτον μὲν οὐ πάσης κινήσεως αἴτιον τὸ κενόν, ἀλλὰ τῆς ἄνω (τὸ γὰρ μανὸν κοῦφον, διὸ καὶ τὸ πῦρ μανὸν εἶναί φασιν, ἔπειτα κινήσεως αἴτιον οὐχ οὕτω τὸ κενὸν ὡς ἐν ᾧ, ἀλλʼ ὥσπερ οἱ ἀσκοὶ τῷ φέρεσθαι αὐτοὶ ἄνω φέρουσι τὸ συνεχές, οὕτω τὸ κενὸν ἄνω φέρει.
But if they mean not a separated one, but nevertheless that some void is in it, this is less impossible, but it happens, first, that the void is the cause not of all motion but of upward motion (for the rare is light, which is why they say that fire also is rare), and second, that the void is the cause of motion not as that "in which", but just as leather skins by being carried upward themselves carry what is continuous with them, so the void carries things upward.
καίτοι πῶς οἷόν τε φορὰν εἶναι κενοῦ ἢ τόπον κενοῦ;
And yet, how is it possible for there to be a motion of the void or a place of the void?
κενοῦ γὰρ γίγνεται κενόν, εἰς ὃ φέρεται.
For there would be a void of a void, into which it is carried.
ἔτι δὲ πῶς ἐπὶ τοῦ βαρέος ἀποδώσουσιν τὸ φέρεσθαι κάτω;
Moreover, how will they account for the downward motion of the heavy?
καὶ δῆλον ὅτι εἰ ὅσῳ ἂν μανότερον καὶ κενώτερον ἢ ἄνω οἰσθήσεται, εἰ ὅλως εἴη κενόν, τάχιστʼ ἂν φέροιτο.
And it is clear that if the rarer and emptier a thing is, the faster it is carried upward, then if there were a pure void, it would be carried fastest of all.
ἴσως δὲ καὶ τοῦτʼ ἀδύνατον κινηθῆναι· λόγος δʼ ὁ αὐτός, ὥσπερ ὅτι ἐν τῷ κενῷ ἀκίνητα πάντα, οὕτω καὶ τὸ κενὸν ὅτι ἀκίνητον· ἀσύμβλητα γὰρ τὰ τάχη.
But perhaps even this is impossible to be moved; and the argument is the same: just as all things are unmoved in the void, so also the void itself is unmoved, for the speeds are incomparable.
ἐπεὶ
δὲ κενὸν μὲν οὔ φαμεν εἶναι, τὰ ἄλλα δʼ ἠπόρηται ἀληθῶς, ὅτι ἢ κίνησις οὐκ ἔσται, εἰ μὴ ἔσται πύκνωσις καὶ μάνωσις, ἢ κυμανεῖ ὁ οὐρανός, ἢ αἰεὶ ἴσον ὕδωρ ἐξ ἀέρος ἔσται καὶ· ἀὴρ ἐξ ὕδατος (δῆλον γὰρ ὅτι πλείων ἀὴρ ἐξ ὕδατος γίγνεται· ἀνάγκη τοίνυν, εἰ μὴ ἔστι πίλησις, ἢ ἐξωθούμενον τὸ ἐχόμενον τὸ ἔσχατον κυμαίνειν ποιεῖν, ἢ ἄλλοθί που ἴσον μεταβάλλειν ἐξ ἀέρος ὕδωρ, ἵνα ὁ πᾶς ὄγκος τοῦ ὅλου ἴσος ᾖ, ἢ μηδὲν κινεῖσθαι· ἀεὶ γὰρ μεθισταμένου τοῦτο συμβήσεται, ἂν μὴ κύκλῳ περιίστηται· οὐκ ἀεὶ δʼ εἰς τὸ κύκλῳ ἡ φορά, ἀλλὰ καὶ εἰς εὐθύ)· οἱ μὲν δὴ διὰ ταῦτα κενόν τι φαῖεν ἂν εἶναι, ἡμεῖς δὲ λέγομεν ἐκ τῶν ὑποκειμένων ὅτι ἔστιν ὕλη μία τῶν ἐναντίων, θερμοῦ καὶ ψυχροῦ καὶ τῶν ἄλλων τῶν φυσικῶν ἐναντιώσεων, καὶ ἐκ δυνάμει ὄντος ἐνεργείᾳ ὂν γίγνεται, καὶ οὐ χωριστὴ μὲν ἡ ὕλη, τὸ δʼ εἶναι ἕτε· ρον, καὶ μία τῷ ἀριθμῷ, εἰ ἔτυχε, χροιᾶς καὶ θερμοῦ καὶ ψυχροῦ.
But since we say there is no void, and the other options have been truly puzzled over—namely, that either there will be no motion unless there is condensation and rarefaction, or the heaven will bulge, or there will always be an equal amount of water from air and air from water (for it is clear that more air is generated from water); therefore, if there is no compression, it is necessary either that what is contiguous being pushed out should make the extremity bulge, or that somewhere else an equal amount of water should change from air, so that the whole bulk of the universe may be equal, or that nothing should move; for this will always happen when a thing shifts its place, unless it circulates in a circle; but the motion is not always circular, but also in a straight line—these people, then, because of these things, would say that there is some void, but we say from our principles that there is one matter of contraries, of hot and cold and of the other natural contrarieties, and that what is in actuality comes to be from what is in potentiality, and that matter is not separable, though its being is different, and it is one in number, if it so happens, for color and hot and cold.