§4.4#14 Τὰς δὲ διαφορὰς καὶ τὰ συμβαίνοντα περὶ αὐτὰ νῦν λέγωμεν.
4 Let us now speak of their differences and the things that happen concerning them.
πρῶτον μὲν οὖν διωρίσθω, καθάπερ φαίνεται πᾶσι, βαρὺ μὲν ἀπλῶς τὸ πᾶσιν ὑφιστάμενον, κοῦφον δὲ τὸ πᾶσιν ἐπιπολάζον.
First, then, let it be defined, as indeed it appears to all, that the absolutely heavy is that which sinks beneath everything, and the light is that which rises to the surface of everything.
ἁπλῶς δὲ λέγω εἴς τε τὸ γένος βλέπων, καὶ ὅσοις μὴ ἀμφότερα ὑπάρχει·
And I say "absolutely" looking to the genus, and in those to which both do not belong.
οἷον φαίνεται πυρὸς μὲν τὸ τυχὸν μέγεθος ἄνω φερόμενον, ἐὰν μή τι τύχῃ κωλῦον ἕτερον, γῆς δὲ κάτω· τὸν αὐτὸν δὲ τρόπον καὶ θᾶττον τὸ πλεῖον.
For example, any size of fire is seen to be carried upward, unless some other thing happens to prevent it, and any size of earth downward; and in the same manner the greater quantity is carried faster.
ἄλλως δὲ βαρὺ καὶ κοῦφον, οἷς ἀμφότερα ὑπάρχει· καὶ γὰρ ἐπιπολάζουσί τισι καὶ ὑφίστανται, καθάπερ ἀὴρ καὶ ὕδωρ·
But in another way heavy and light are said of those to which both belong; for indeed they rise to the surface of some things and sink beneath others, as do air and water.
ἁπλῶς μὲν γὰρ οὐδέτερον τούτων κοῦφον ἢ βαρύ· γῆς μὲν γὰρ ἄμφω κουφότερα (ἐπιπολάζει γὰρ αὐτῇ τὸ τυχὸν αὐτῶν μόριον), πυρὸς δὲ βαρύτερα (ὑφίσταται γὰρ αὐτῶν ὁπόσον ἂν μόριον), πρὸς ἑαυτὰ δὲ ἀπλῶς τὸ μὲν βαρυ τὸ δὲ κοῦφον·
For absolutely neither of these is light or heavy; for both are lighter than earth (for any part of them rises to its surface), but heavier than fire (for whatever part of them sinks beneath it).
ἀὴρ μὲν γὰρ ὁπόσος ἂν ᾖ, ἐπιπολάζει ὕδατι, ὕδωρ δὲ ὁπόσον ἂν ᾖ, ἀέρι ὑφίσταται.
But in relation to each other, simply the one is heavy and the other light; for air, in whatever quantity it may be, rises to the surface of water, and water, in whatever quantity it may be, sinks beneath air.
ἐπεὶ δὲ καὶ τῶν ἄλλων τὰ μὲν ἔχει βάρος τὰ δὲ κουφότητα, δῆλον ὅτι τούτων μὲν αἰτία πάντων ἡ ἐν τοῖς ἀσυνθέτοις διαφορά·
And since among other things also, some have heaviness and others lightness, it is clear that the cause of all these is the difference in the uncompounded things.
κατὰ γὰρ τὸ ἐκείνων τετυχηκέναι τοῦ μὲν πλεῖον τοῦ δʼ ἔλαττον, ἔσται τὰ μὲν κοῦφα τὰ δὲ βαρέα τῶν σωμάτων.
For according to having obtained more of the one of them and less of the other, some of the bodies will be light and others heavy.
ὥστε περὶ ἐκείνων λεκτέον· τἆλλα γὰρ ἀκολουθεῖ τοῖς πρώτοις, ὅπερ ἔφαμεν χρῆναι ποιεῖν καὶ τοὺς διὰ τὸ πλῆρες τὸ βαρὺ λέγοντας καὶ διὰ τὸ κενὸν τὸ κοῦφον.
So that we must speak about those; for the others follow the first, which is just what we said those ought to do who say that the heavy is due to the full and the light is due to the void.
συμβαίνει δὴ μὴ πανταχοῦ ταὐτὰ βαρέα δοκεῖν εἶναι καὶ κοῦφα διὰ τὴν τῶν πρώτων διαφοράν·
It happens, then, that because of the difference of the first, the same things do not seem to be heavy and light everywhere.
λέγω δʼ οἷον ἐν μὲν ἀέρι βαρύτερον ἔσται ταλαντιαῖον ξύλον μολίβδου μναιαίου, ἐν δὲ ὕδατι κουφότερον·
I mean, for example, that in air a wooden log of one talent will be heavier than a mina of lead, but in water it will be lighter.
αἴτιον δʼ ὅτι πάντα βάρος ἔχει πλὴν πυρὸς καὶ κουφότητα πλὴν γῆς.
And the cause is that all things have heaviness except fire, and lightness except earth.
γῆν μὲν οὖν καὶ ὅσα γῆς ἔχει πλεῖστον, πανταχοῦ βάρος ἔχειν ἀναγκαῖον, ὕδωρ δὲ πανταχοῦ πλὴν ἐν γῇ, ἀέρα δὲ πλὴν ἐν ὕδατι καὶ γῇ· ἐν τῇ αὑτοῦ γὰρ χώρᾳ πάντα βάρος ἔχει πλὴν πυρός, καὶ ὁ ἀήρ.
Earth, then, and whatever has most of earth, must of necessity have heaviness everywhere, water everywhere except in earth, and air except in water and earth; for in its own place everything has heaviness except fire, and air does too.
σημεῖον δʼ ὅτι ἕλκει πλεῖον ὁ πεφυσημένος ἀσκὸς τοῦ κενοῦ·
And the sign is that the inflated skin-bag weighs more than the empty one.
ὥστʼ εἴ τι ἀέρος ἔχει πλεῖον ἢ γῆς καὶ ὕδατος, ἐν μὲν ὅδατι ἐνδέχεται κουφότερον εἶναι τινός, ἐν δὲ ἀέρι βαρύτερον· ἀέρι μὲν γὰρ οὐκ ἐπιπολάζει, τῷ δὲ ὕδατι ἐπιπολάζει.
So that if something has more of air than of earth and water, in water it can be lighter than something, but in air heavier; for it does not rise to the surface of air, but it does rise to the surface of water.
ὅτι δʼ ἔστι τι ἁπλῶς κοῦφον καὶ ἁπλῶς βαρύ, ἐκ τῶνδʼ ἐστὶ φανερόν (λέγω δʼ ἀπλῶς κοῦφον ὃ ἀεὶ ἄνω καὶ βαρὺ ὃ ἀεὶ κάτω πέφυκε φέρεσθαι μη κωλυόμενον·
But that there is something absolutely light and absolutely heavy is clear from what follows (and I mean by absolutely light that which is naturally carried always upward, and heavy that which is naturally carried always downward, when not prevented).
τοιαῦτα γὰρ ἔστι, καὶ οὐχ ὥσπερ οἔονταί τινες πάντʼ ἔχειν βάρος· βαρὺ μὲν γὰρ δοκεῖ τισὶν εἶναι καὶ ἑτέροις, καὶ ἀεὶ φέρεσθαι πρὸς τὸ μέσον.
For such things exist, and it is not as some think, that all things have heaviness; for indeed to some it seems that the other things also are heavy, and are always carried to the center.