and an enmattered principle in matter, through which 'for heaven to be' is different from 'for this particular heaven to be'? If heaven cannot do by will what it does by motion, how is it an eternal god, effecting eternal life without will? If among eternal things heaven does not effect eternal life (for they have this from their own nature), and things that are generated and corruptible do not live eternally, where is the eternal life which heaven effects? If the motion of heaven is useful not only for the generation of things that come to be, but also for the corruption of things that are corrupted, how is heaven a god and its activity eternal life, through which corruptible things are corrupted? If it is not possible for something from matter to be co-ungenerated with matter, how is heaven ungenerated, being from matter? If that which is from both is posterior to both, how is heaven, which is from matter and form, co-eternal with both? If the form is not from matter, but from the maker, how is heaven, having its matter from one source and its form from another, ungenerated? If heaven is a material body and has a spherical shape and is ungenerated, how does it not have both from matter, both being what it is and having what it has? If matter is that which primarily underlies and is inherent in things that come to be from it in their own right, how does heaven, being ungenerated, have matter underlying and inherent in it like generated things do? 53. From the same argument. Since heaven is a divine body, for this reason it has a circular body, which by nature is always moved in a circle. Why then is not the whole body of heaven of this kind? Because it is necessary for something of the body that moves in a circle to remain at the center, but it is possible for no part of this body to remain, either at all or at the center. For its natural motion would have been toward the center; but it moves by nature in a circle; for the motion would not have been eternal; for nothing contrary to nature is eternal. And what is contrary to nature is posterior to what is according to nature, and in generation, what is contrary to nature is a kind of deviation from what is according to nature. It is necessary, therefore, that there be earth; for this rests at the center. But if there is earth, it is necessary that there also be fire; for if one of the contraries exists by nature, it is necessary that the other also exist by nature, if indeed it is a contrary, and that there be some nature of it; for the same matter of contraries is also prior to privation, I mean, for example, the hot to the cold. But if indeed there is fire and earth, it is necessary that there also be bodies between them; for each has a contrariety with respect to each of the elements. And since these exist, it is necessary that there be generation, because it is not possible for any of them to be eternal; for the contraries act on and are acted upon by each other, and are destructive of each other. Furthermore, it is not reasonable that there be any eternal movable thing whose motion cannot be eternal according to nature; and motion belongs to these. That it is necessary, therefore, for there to be generation is clear from these things. And if generation, it is necessary that there also be another corruption, either one or more; for according to the whole it is similarly necessary for the elements of the bodies to be disposed to each oth

καὶ λόγον ἔνυλον ἐν τῇ ὕλῃ, δι' ὃν ἕτερον τὸ οὐρανῷ εἶναι τῷ τόδε οὐρανὸν εἶναι; Eἰ οὐ δύναται ὁ οὐρανὸς ποιῆσαι τῇ βουλήσει ἃ ποιεῖ τῇ κινήσει, πῶς θεὸς οὗτος ἀΐδιος, ἀΐδιον ἐνεργῶν ζωὴν ἀβουλήτως; Eἰ ἐν τοῖς ἀϊδίοις οὐκ ἐνεργεῖ ὁ οὐρανὸς τὴν αἰώνιον ζωήν (ἔχουσι γὰρ ταύτην ἐκ τῆς οἰκείας φύσεως), τὰ γενητὰ δὲ καὶ φθαρτὰ αἰωνίως οὐ ζῶσι, ποῦ ἡ αἰώνιος ζωή, ἣν ἐνεργεῖ ὁ οὐρανός· Eἰ μὴ μόνον πρὸς γένεσιν τῶν γιγνομένων, ἀλλὰ καὶ πρὸς τὴν τῶν φθειρομένων φθο ρὰν χρησίμη ἡ τοῦ οὐρανοῦ κίνησις, πῶς θεὸς ὁ οὐρανὸς καὶ ἡ ἐνέργεια αὐτοῦ ζωὴ αἰώνιος, δι' ἧς φθείρεται τὰ φθαρτά; Eἰ ἐκ τῆς ὕλης συναγένητον τῇ ὕλῃ οὐ δυνατὸν εἶναι, πῶς ἀγένητος ὁ οὐρανός, ὁ ὢν ἐκ τῆς ὕλης; Eἰ τὸ ἐξ ἀμφοτέρων ὕστερον ἀμφοτέρων, πῶς ὁ οὐρανός, ὁ ὢν ἐκ τῆς ὕλης καὶ τοῦ εἴδους, συναΐδιός ἐστιν ἀμφοτέροις; Eἰ τὸ εἶδος οὐκ ἐκ τῆς ὕλης, ἀλλὰ ἐκ τοῦ ποιοῦντος, πῶς ὁ οὐρανός, ἄλλοθεν ἔχων τὴν ὕλην καὶ ἑτέρωθεν τὸ εἶδος, ἀγένητός ἐστιν; Eἰ ὑλικόν ἐστι σῶμα ὁ οὐρανὸς καὶ σφαιρικὸν ἔχει τὸ σχῆμα καὶ ἔστιν ἀγένητος, πῶς οὐκ ἀμφότερα ἔχει ἐκ τῆς ὕλης, καὶ τὸ εἶναι ὅ ἐστι καὶ τὸ ἔχειν ὃ ἔχει; Eἰ ἔστιν ἡ ὕλη τὸ τοῖς καθ' αὑτὸ ἐξ αὐτῆς γιγνομένοις πρώτως ὑποκείμενον καὶ ἐνυπάρχον, πῶς ἀγένητος ὢν ὁ οὐρανός, ὡς τὰ γενητὰ τὴν ὕλην ἔχει ὑποκειμένην τε καὶ ἐνυπάρχουσαν; νγ. Ἐκ τοῦ αὐτοῦ λόγου. Ἐπειδὴ ὁ οὐρανὸς σῶμά τι θεῖον, διὰ τοῦτο ἔχει τὸ ἐγκύκλιον σῶμα, ὃ φύσει κινεῖται κύκλῳ ἀεί. ∆ιὰ τί οὖν οὐχ ὅλον τὸ σῶμα τοῦ οὐρανοῦ τοιοῦτον; Ὅτι ἀνάγκη μένειν τι τοῦ σώματος τοῦ φερομένου κύκλῳ τὸ ἐπὶ τῷ μέσῳ, τούτου δ' οὐδὲν οἷόν τε μένειν μόριον οὔθ' ὅλως οὔτ' ἐπὶ τοῦ μέ σου. Καὶ γὰρ ἂν ἡ κατὰ φύσιν κίνησις ἦν αὐτοῦ ἐπὶ τὸ μέσον· φύσει δὲ κύκλῳ κινεῖται· οὐ γὰρ ἂν ἦν ἀΐδιος ἡ κί νησις· οὐθὲν γὰρ παρὰ φύσιν ἀΐδιον. Ὕστερον δὲ τὸ παρὰ φύσιν τοῦ κατὰ φύσιν, καὶ ἔκστασίς τίς ἐστιν ἐν τῇ γενέσει τὸ παρὰ φύσιν τοῦ κατὰ φύσιν. Ἀνάγκη τοίνυν γῆν εἶναι· τοῦτο γὰρ ἠρεμεῖ ἐπὶ τοῦ μέσου. Ἀλλὰ μὴν εἰ γῆν, ἀνάγκη καὶ πῦρ εἶναι· τῶν γὰρ ἐναντίων εἰ θάτερον φύσει, ἀνάγκη καὶ θάτερον εἶναι φύσει, ἐάνπερ ᾖ ἐναντίον, καὶ εἶναί τινα αὐτοῦ φύσιν· ἡ γὰρ αὐτὴ ὕλη τῶν ἐναντίων καὶ τῆς στερή σεως προτέρα, λέγω δὲ οἷον τὸ θερμὸν τοῦ ψυχροῦ. Ἀλλὰ μὴν εἴπερ ἔστι πῦρ καὶ γῆ, ἀνάγκη καὶ τὰ μεταξὺ αὐτῶν εἶναι σώματα· ἐναντίωσιν γὰρ ἕκαστον ἔχει πρὸς ἕκαστον τῶν στοιχείων. Τούτων δὲ ὑπαρχόντων ἀνάγκη γένεσιν εἶναι διὰ τὸ μηδὲν οἷόν τ' αὐτῶν εἶναι ἀΐδιον· πάσχει γὰρ καὶ ποιεῖ τὰ ἐναντία ὑπ' ἀλλήλων, καὶ φθαρτικὰ ἀλλήλων ἐστίν. Ἔτι δὲ οὐκ εὔλογον εἶναί τι κινητὸν ἀΐδιον, οὗ μὴ ἐνδέχεται κατὰ φύσιν εἶναι τὴν κίνησιν ἀΐδιον· τούτων δ' ἐστὶ κίνησις. Ὅτι μὲν τοίνυν ἀναγκαῖον εἶναι γένεσιν, ἐκ τούτων δῆλον. Eἰ δὲ γένεσιν, ἀναγκαῖον εἶναι καὶ ἄλλην φθοράν, ἢ μίαν ἢ πλείους· κατὰ γὰρ τὴν τοῦ ὅλου ὡσαύτως ἀναγκαῖον ἔχειν τὰ στοιχεῖα τῶν σωμάτων πρὸς ἄλ