ἐπεὶ δὲ πάντες ἐπῄνεσαν τὸν Λεύκιον, εὖ γʼ ἔφην ὅτι καλῷ λόγῳ καλὴν ἀναλογίαν προσέθηκας· οὐ γὰρ ἀποστερητέον σε τῶν ἰδίων κἀκεῖνος ἐπιμειδιάσας οὐκοῦν ἔφη καὶ δεύτερον ἀναλογίᾳ προσχρηστέον, ὅπως μὴ τῷ ταὐτὰ πάσχειν ὑπὸ ταὑτοῦ μόνον ἀλλὰ καὶ τῷ ταὐτὰ ποιεῖν ταὐτὸν ἀποδείξωμεν τῇ γῇ τὴν σελήνην προσεοικυῖαν. ὅτι μὲν γὰρ οὐδὲν οὕτως τῶν περὶ τὸν ἥλιον γιγνομένων ὅμοιόν ἐστιν, ὡς ἔκλειψις ἡλίου δύσει, δότε μοι, ταύτης ἔναγχος τῆς συνόδου μνησθέντες, ἣ πολλὰ μὲν ἄστρα πολλαχόθεν τοῦ οὐρανοῦ διέφηνεν εὐθὺς ἐκ μεσημβρίας ἀρξαμένη, κρᾶσιν δʼ οἵαν τὸ λυκαυγὲς τῷ ἀέρι παρέσχεν· εἰ δὲ μή, Θέων ἡμῖν οὗτος τὸν Μίμνερμον ἐπάξει καὶ τὸν Κυδίαν καὶ τὸν Ἀρχίλοχον, πρὸς δὲ τούτοις τὸν Στησίχορον καὶ τὸν Πίνδαρον, ἐν ταῖς ἐκλείψεσιν ὀλοφυρομένους ἄστρον φανερώτατον κλεπτόμενον καί μέσῳ ἄματι νύκτα γινομένην καὶ τὴν ἀκτῖνα τοῦ ἡλίου σκότου ἀτραπὸν […] φάσκοντας· ἐπὶ πᾶσι δὲ τὸν Ὅμηρον νυκτὶ καὶ ζόφῳ τὰ πρόσωπα κατέχεσθαι τῶν ἀνθρώπων λέγοντα καὶ τὸν ἣλιον ἐξαπολωλέναι τοῦ οὐρανοῦ περὶ τὴν σελήνην καὶ […] τοῦτο γίγνεσθαι πέφυκε τοῦ μὲν φθίνοντος μηνὸς τοῦ δʼ ἱσταμένοιο. τὰ λοιπὰ δʼ οἶμαι ταῖς μαθηματικαῖς ἀκριβείαις εἰς τὸν […] ἐξῆχθαι καὶ βέβαιον, ὡς ἥ γε νύξ ἐστι σκιὰ γῆς, ἡ δʼ ἔκλειψις τοῦ ἡλίου σκιὰ σελήνης, ὅταν ἡ ὄψις ἐν αὐτῇ γένηται. δυόμενος γὰρ ὑπὸ τῆς γῆς ἀντιφράττεται πρὸς τὴν ὄψιν, ἐκλιπὼν δʼ ὑπὸ τῆς σελήνης· ἀμφότεραι δʼ εἰσὶν ἐπισκοτήσεις, ἀλλʼ ἡ μὲν δυτικὴ τῆς γῆς ἡ δʼ ἐκλειπτικὴ τῆς σελήνης, τῇ σκιᾷ καταλαμβανούσης τὴν ὄψιν. ἐκ δὲ τούτων εὐθεώρητον τὸ γιγνόμενον. εἰ γὰρ ὅμοιον τὸ πάθος, ὅμοια τὰ ποιοῦντα· τῷ γὰρ αὐτῷ ταὐτὰ συμβαίνειν ὑπὸ τῶν αὐτῶν ἀναγκαῖόν ἐστιν. εἰ δʼ οὐχ οὕτω τὸ περὶ τὰς ἐκλείψεις σκότος βύθιόν ἐστιν οὐδʼ ὁμοίως τῇ νυκτὶ πιέζει τὸν ἀέρα, μὴ θαυμάζωμεν· οὐσία μὲν γὰρ ἡ αὐτὴ τοῦ τὴν νύκτα ποιοῦντος καὶ τοῦ τὴν ἔκλειψιν σώματος, μέγεθος δʼ οὐκ ἴσον· ἀλλʼ Αἰγυπτίους μὲν ἑβδομηκοστόδυον οἶμαι φάναι μόριον εἶναι τὴν σελήνην, Ἀναξαγόραν δʼ ὅση Πελοπόννησος. Ἀρίσταρχος δὲ τὴν διάμετρον τῆς γῆς πρὸς τὴν διάμετρον τῆς σελήνης λόγον ἔχουσαν ἀποδείκνυσιν, ὃς ἐλάττων μὲν ἢ ἑξήκοντα πρὸς δεκαεννέα, μείζων δʼ ἢ ὡς ἑκατὸν ὀκτὼ πρὸς τεσσαράκοντα τρίʼ ἐστίν. ὅθεν ἡ μὲν γῆ παντάπασι τῆς ὄψεως τὸν ἣλιον ἀφαιρεῖται διὰ μέγεθος· μεγάλη γὰρ ἡ ἐπιπρόσθησις καὶ χρόνον ἔχουσα τὸν τῆς νυκτός· ἡ δὲ σελήνη κἂν ὅλον ποτὲ κρύψῃ τὸν ἣλιον, οὐκ ἔχει χρόνον οὐδὲ πλάτος ἡ ἔκλειψις, ἀλλὰ περιφαίνεταί τις αὐγὴ περὶ τὴν ἴτυν, οὐκ ἐῶσα βαθεῖαν γενέσθαι τὴν σκιὰν καὶ ἄκρατον. Ἀριστοτέλης δʼ ὁ παλαιὸς αἰτίαν τοῦ πλεονάκις τὴν σελήνην ἐκλείπουσαν ἢ τὸν ἣλιον καθορᾶσθαι πρὸς ἄλλαις τισὶ καὶ ταύτην ἀποδίδωσιν· ἥλιον γὰρ ἐκλείπειν σελήνης ἀντιφράξει, σελήνην δὲ […] . ὁ δὲ Ποσειδώνιος ὁρισάμενος οὕτω τόδε τὸ πάθος ἔκλειψίς ἐστιν ἡλίου σύνοδος σκιᾶς σελήνης, ἧς τὴν ἔκλειψιν ἐκείνοις γὰρ μόνοις ἔκλειψίς ἐστιν, ὧν ἂν ἡ σκιὰ τῆς σελήνης καταλαβοῦσα τὴν ὄψιν ἀντιφράξαι πρὸς τὸν ἥλιον· ὁμολογῶν δὲ σκιὰν τῆς σελήνης φέρεσθαι πρὸς ἡμᾶς, οὐκ οἶδʼ ὅ τι λέγειν ἑαυτῷ καταλέλοιπεν ἄστρου δὲ σκιὰν ἀδύνατον γενέσθαι· τὸ γὰρ ἀφώτιστον σκιὰ λέγεται, τὸ δὲ φῶς οὐ ποιεῖ σκιὰν ἀλλʼ ἀναιρεῖν πέφυκεν.
Now when all the company began highly to commend Lucius’s harangue; This is excellently well done of you, Lucius (said I to him), that you have to so fine a discourse added as fine a proportion, for you must not be defrauded of that which is your due.
Then Lucius, smiling, thus went on: I have yet a second proportion to be added to the former, by which we will clearly demonstrate that the moon altogether resembles the earth, not only because they suffer and receive the same accidents from the same cause, but because they work the same effect on the same object. For you will without difficulty, I suppose, grant me that, of all the accidents which befall the sun, there is none so like to his setting as his eclipse, especially if you but call to mind that recent conjunction which, beginning at noonday, showed us many stars in many places of the heavens, and wrought a temperature in the air like that of the twilight. But if you will not grant me this, our friend Theon here will bring us a Mimnermus, a Cydias, an Archilochus, and besides these, a Stesichorus and a Pindar, lamenting that in eclipses the world is robbed of its brightest light, and saying that night comes on in the midst of the day, and that the rays of the sun wander in the path of darkness; but above all he will produce Homer, saying that the faces of men are in eclipses seized upon by night and darkness, and the sun is quite lost out of heaven by the conjunction of the moon. And […] it is natural that this should happen, When one moon’s going, and another comes. / For the rest of the demonstration is, in my opinion, as certain and exactly concluding, as are the acute arguments of the mathematics. As night is the shadow of the earth, so the eclipse of the sun is the shadow of the moon, when it stands in the way of our sight. For the sun is at his setting kept from our sight by the interposition of the earth, and at his eclipse by that of the moon. Now both of these are obscurations; but that of his setting is from the earth, and that of his being eclipsed from the moon, their shadows intercepting our sight. Now the consequences of these things are easily understood. For if the effect is alike, the efficient causes are also alike; because it is of necessity that the same effects, happening in the same subjects, proceed from the same efficients. Now if the darkness in eclipses is not so profound, nor does so forcibly and entirely seize the air, as does the night, we are not to wonder at it; for the substance of the body which makes the night, and of that which causes the eclipse, is indeed the same, though their greatness is not equal. For the Egyptians, if I am not mistaken, hold that the moon is in bigness the two and seventieth part of the earth; and Anaxagoras says, she is as big as Peloponnesus. And Aristarchus shows the overthwart line or diameter of the moon to have a proportion to that of the earth which is less than if sixty were compared to nineteen, and somewhat greater than an hundred and eight compared to forty and three. Whence it happens that the earth, by reason of its greatness, wholly withdraws the sun from our sight; for it is a great obstacle and opposition, and lasts all the night. But although the moon sometimes hides all the sun, yet that eclipse continues not so long nor is so far extended, but there always appears about the circumference a certain brightness, which permits not the darkness to be black, deep, and perfectly obscure.
And Aristotle (I mean the ancient philosopher of that name) rendering the reason why there are oftener seen to happen eclipses of the moon than of the sun, among other causes alleges this, that the sun is eclipsed by the interposition of the moon, and the moon by that of the earth, which is much greater and consequently oftener opposes itself. And Posidonius thus defines this accident: The eclipse of the sun is the conjunction of the sun and moon, the shadow of which darkens our sight. For there is no eclipse except to those whose sight the shadow of the moon intercepting hinders them from seeing the sun. Now in confessing that the shadow of the moon descends down to us, I know not what he has left himself to say. It is certainly impossible for a star to cast a shadow; for that which is not enlightened is called a shadow, and light makes no shadow, but on the contrary drives it away.
ἀλλὰ τί δή ἔφη μετὰ τοῦτο τῶν τεκμηρίων ἐλέχθη; κἀγώ τὴν αὐτήν ἔφην ἐλάμβανεν ἡ σελήνη ἔκλειψιν. ὀρθῶς εἶπεν ὑπέμνησας ἀλλὰ δὴ πότερον ὡς πεπεισμένων ὑμῶν καὶ τιθέντων ἐκλείπειν τὴν σελήνην ὑπὸ τοῦ σκιάσματος ἁλισκομένην ἤδη τρέπωμαι πρὸς τὸν λόγον, ἢ βούλεσθε μελέτην ποιήσωμαι καὶ ἀπόδειξιν ὑμῖν τῶν ἐπιχειρημάτων ἕκαστον ἀπαριθμήσας; νὴ Δίʼ εἶπεν ὁ Θέων τούτοις καὶ ἐμμελέτησον· ἐγὼ δὲ καὶ, πειθοῦς τινος δέομαι, ταύτῃ μόνον ἀκηκοὼς, ὡς ἐπὶ μίαν εὐθεῖαν τῶν τριῶν σωμάτων γιγνομένων, γῆς καὶ ἡλίου καὶ σελήνης, αἱ ἐκλείψεις συντυγχάνουσιν ἡ γὰρ γῆ τῆς σελήνης ἢ πάλιν ἡ σελήνη τῆς γῆς ἀφαιρεῖται τὸν ἣλιον· ἐκλείπει γὰρ οὗτος μὲν σελήνης σελήνη δὲ γῆς ἐν μέσῳ τῶν τριῶν ἱσταμένης· ὧν γίγνεται τὸ μὲν ἐν συνόδῳ τὸ δʼ ἐν διχομηνίᾳ καὶ ὁ Λεύκιος ἔφη σχεδὸν μέντοι τῶν λεγομένων κυριώτατα ταῦτʼ ἐστί· πρόσλαβε δὲ πρῶτον, εἰ βούλει, τὸν ἀπὸ τοῦ σχήματος τῆς σκιᾶς λόγον· ἔστι γὰρ κῶνος, ἅτε καὶ μεγάλου πυρὸς; ἢ φωτὸς σφαιροειδοῦς ἐλάττονα σφαιροειδῆ δὲ περιβάλλοντος ὄγκον· ὅθεν ἐν ταῖς ἐκλείψεσι τῆς σελήνης αἱ περιγραφαὶ τῶν μελαινομένων πρὸς τὰ λαμπρὰ τὰς ἀποτομὰς περιφερεῖς ἴσχουσιν· ἃς γὰρ ἂν στρογγύλῳ στρογγύλῳ προσμῖξαν ἢ δέξηται τομὰς ἢ παράσχῃ, πανταχόσε χωροῦσαι διʼ ὁμοιότητα γίγνονται κυκλοτερεῖς; δεύτερον οἶμαί σε γιγνώσκειν, ὅτι σελήνης; μὲν ἐκλείπει πρῶτα μέρη τὰ πρὸς ἀπηλιώτην, ἡλίου δὲ τὰ πρὸς δύσιν, κινεῖται δʼ ἡ μὲν σκιὰ τῆς γῆς ἐπὶ τὴν ἑσπέραν ἀπὸ τῶν ἀνατολῶν, ἥλιος δὲ καὶ σελήνη τοὐναντίον ἐπὶ τὰς ἀνατολάς. ταῦτα γὰρ ἰδεῖν τε παρέχει τῇ αἰσθήσει τὰ φαινόμενα κἀκ λόγων οὐ πάνυ τι μακρῶν μαθεῖν ἔστιν· ἐκ δὲ τούτων ἡ αἰτία βεβαιοῦται τῆς ἐκλείψεως. ἐπεὶ γὰρ ἥλιος μὲν ἐκλείπει καταλαμβανόμενος, σελήνη δʼ ἀπαντῶσα τῷ ποιοῦντι τὴν ἔκλειψιν, εἰκότως μᾶλλον δʼ ἀναγκαίως ὁ μὲν ὄπισθεν ἁλίσκεται πρῶτον ἡ δʼ ἔμπροσθεν ἄρχεται γὰρ ἐκεῖθεν ἡ ἐπιπρόσθησις, ὅθεν πρῶτον ἐπιβάλλει τὸ ἐπιπροσθοῦν ἐπιβάλλει δʼ ἐκείνῳ μὲν ἀφʼ ἑσπέρας ἡ σελήνη πρὸς αὐτὸν ἁμιλλωμένη, ταύτῃ δʼ ἀπὸ τῶν ἀνατολῶν, ὡς πρὸς τοὐναντίον ὑποφερομένη. τρίτον τοίνυν ἔτι τὸ τοῦ χρόνου λάβε καὶ τὸ τοῦ μεγέθους τῶν ἐκλείψεων αὐτῆς. ὑψηλὴ μὲν ἐκλείπουσα καὶ ἀπόγειος ὀλίγον ἀποκρύπτεται χρόνον, πρόσγειος δὲ καὶ ταπεινὴ αὐτὸ τοῦτο παθοῦσα σφόδρα πιέζεται καὶ βραδέως ἐκ τῆς σκιᾶς ἄπεισι· καίτοι ταπεινὴ μὲν οὖσα τοῖς μεγίστοις χρῆται κινήμασιν, ὑψηλὴ δὲ τοῖς ἐλαχίστοις. ἀλλὰ τὸ αἴτιον ἐν τῇ σκιᾷ τῆς διαφορᾶς ἔστιν· εὐρυτάτη γὰρ οὖσα περὶ τὴν βάσιν, ὥσπερ οἱ κῶνοι, συστελλομένη τε κατὰ μικρὸν εἰς ὀξὺ τῇ κορυφῇ καὶ λεπτὸν ἀπολήγει πέρας. ὅθεν ἡ σελήνη ταπεινὴ μὲν ἐμπεσοῦσα τοῖς μεγίστοις λαμβάνεται κύκλοις ὑπʼ αὐτῆς καὶ διαπερᾷ τὸ βύθιον καὶ σκοτωδέστατον ἄνω δʼ οἷον ἐν τενάγει διὰ λεπτότητα τοῦ σκιεροῦ χρανθεῖσα ταχέως ἀπαλλάττεται. παρίημι δʼ ὅσα χωρὶς ἰδίᾳ πρὸς τὰς βάσεις καὶ τὰς διαφορήσεις ἐλέχθη· καὶ γὰρ ἐκεῖναι μέχρι γε τοῦ ἐνδεχομένου προσίενται τὴν αἰτίαν· ἀλλʼ ἐπανάγω πρὸς τὸν ὑποκείμενον λόγον ἀρχὴν ἔχοντα τὴν αἴσθησιν. ὁρῶμεν γὰρ ὅτι πῦρ ἐκ τόπου σκιεροῦ διαφαίνεται καὶ διαλάμπει μᾶλλον εἴτε παχύτητι τοῦ σκοτώδους ἀέρος, οὐ δεχομένου τὰς ἀπορρεύσεις καὶ διαχύσεις ἀλλὰ συνέχοντος ἐν ταὐτῷ τὴν οὐσίαν καὶ σφίγγοντος· εἴτε τῆς αἰσθήσεως; τοῦτο πάθος ἐστίν, ὡς τὰ θερμὰ παρὰ τὰ ψυχρὰ θερμότερα καὶ τὰς ἡδονὰς παρὰ τοὺς πόνους σφοδροτέρας, οὕτω τὰ λαμπρὰ φαίνεσθαι παρὰ τὰ σκοτεινὰ φανερά, τοῖς διαφόροις πάθεσιν ἀντεπιτείνοντα τὴν φαντασίαν. ἔοικε δὲ πιθανώτερον εἶναι τὸ πρότερον· ἐν γὰρ ἡλίῳ πᾶσα πυρὸς φύσις οὐ μόνον τὸ λαμπρὸν ἀπόλλυσιν, ἀλλὰ τῷ εἴκειν γίγνεται δύσεργος καὶ ἀμβλυτέρα· σκίδνησι γὰρ ἡ θερμότης; καὶ διαχεῖ τὴν δύναμιν. εἴπερ οὖν ἡ σελήνη πυρὸς εἴληχε βληχροῦ καὶ ἀδρανοῦς, ἄστρον οὖσα θολερώτερον, ὥσπερ αὐτοὶ λέγουσιν, οὐδὲν ὧν πάσχουσα φαίνεται νῦν, ἀλλὰ τἀναντία πάντα πάσχειν αὐτὴν προσῆκόν ἐστι, φαίνεσθαι μὲν ὅτε κρύπτεται, κρύπτεσθαι δʼ ὁπηνίκα φαίνεται· τουτέστι κρύπτεσθαι μὲν τὸν ἄλλον χρόνον ὑπὸ τοῦ περιέχοντος αἰθέρος ἀμαυρουμένην, ἐκλάμπειν δὲ καὶ γίγνεσθαι καταφανῆ δἰ ἓξ μηνῶν καὶ πάλιν διὰ πέντε τῇ σκιᾷ τῆς γῆς ὑποδυομένην. αἱ γὰρ πέντε καὶ ἑξήκοντα καὶ τετρακόσιαι περίοδοι τῶν ἐκλειπτικῶν πανσελήνων τὰς τέσσαρας καὶ τετρακοσίας ἑξαμήνους ἔχουσι τὰς δʼ ἄλλας πενταμήνους. ἔδει τοίνυν διὰ τοσούτων χρόνων φαίνεσθαι τὴν σελήνην ἐν τῇ σκιᾷ λαμπρυνομένην· ἡ δʼ ἐν τῇ σκιᾷ μὲν ἐκλείπει καὶ ἀπόλλυσι τὸ φῶς, ἀναλαμβάνει δʼ αὖθις, ὅταν ἐκφύγῃ τὴν σκιάν, καὶ φαίνεταί γε πολλάκις ἡμέρας, ὡς πάντα μᾶλλον ἢ πύρινον οὖσα σῶμα καὶ ἀστεροειδές.
But what arguments, said he, were alleged after this?
The moon, answered I then, suffered the same eclipse.
You have done well, replied he, to put me in mind of it. But would you have me go on and prosecute the rest of the discourse, as if you had already supposed and granted that the moon is eclipsed, being intercepted within the shadow of the earth? Or shall I take for the subject of a declamation the making a demonstration of it, by rehearsing to you all the arguments, one after another?
Nay, by Jove, said Theon, let this be the argument of your discourse. For I indeed stand in need of some persuasion, having only heard that when these three bodies, the earth, the moon, and the sun, are in a direct line, then eclipses happen; for that either the earth takes the sun from the moon, or the moon takes him from the earth. For the sun suffers an eclipse when the moon, and the moon when the earth, is in the midst of the three; of which the one happens in the conjunction or new moon, and the other in the opposition or when the moon is full.
Then said Lucius: These are the principal points, and the summary of what is said. But in the first place, if you please, take the argument drawn from the form and figure of the shadow. For this is a cone, as it must be when a great fire or light that is spherical encompasses a mass that is also globular but less; whence it comes that, in the eclipses of the moon, the circumscriptions of the black and dark from the clear and luminous have their sections always round. For the sections given or received by one round body applied to another, which way soever they go, do by reason of the similitude always keep a circular form. Now as for the second argument, I suppose you understand that the first part which is eclipsed in the moon is always that which looks towards the east, and in the sun that which regards the west. Now the shadow of the earth moves from the east to the west, but the sun and moon from the west eastward. The experience of the appearances gives us a visible knowledge of this, nor is there need of many words to make us fully understand it; and from these suppositions the cause of the eclipse is confirmed. For, inasmuch as the sun is eclipsed by being overtaken, and the moon by meeting that which makes the eclipse, it probably or rather necessarily follows that the one is surprised behind, and the other before. For the obstruction begins on that side whence that which causes it first approaches. Now the moon comes upon the sun from the west, as striving in course with him and hastening after him; but the shadow of the earth comes from the east, as that which has a contrary motion.
The third argument is taken from the time and greatness of the eclipses. For the moon, if she is eclipsed when she is on high in her apogee (or at her farthest distance from the earth), continues but a little while in her defect or want of light; but when she suffers the same accident being low and in her perigee (or near the earth), she is very much oppressed, and slowly gets out of the shadow; and yet, when she is low, she moves swifter, and when high, slower. But the cause of the difference is in the shadow, which is, like pyramids, broadest at the bottom or basis; and, growing still narrower by little and little, terminates in a sharp point at the top. Whence it comes, that when she is low, she is embarrassed within greater circles, traversing the bottom of the shadow and what is most obscure and dark; but when she is high, being through the narrowness of the shadow (as it were) but in a shallow puddle, by which she is sullied, she immediately gets out again. I omit what was said particularly about the bases and disposition of parts, for these admit of a rational explanation, so far as this is possible; but I return to the subject properly before us, which has its foundation in our senses. For we see that fire shines forth and appears brighter out of a dark and shady place, through the thickness of the caliginous air, which admits no effluxions or diffusions of the fire’s virtue, but keeps in and contains its substance within itself. Or rather,—if this is a passion of the senses,—as hot things, when near to cold ones, are felt to be hotter, and pleasures immediately after pains are found more vehement, so things that are bright appear better when they are near to such as are obscure, the imagination being more strained and extended by means of different passions. But there seems to be a greater appearance of probability in the first reason. For in the sun, all the nature of fire not only loses its faculty of illuminating, but is also rendered duller and more unapt to burn, because the heat of the sun dissipates and scatters all its force.
If it were then true that the moon, being, as the Stoics say, a muddy and troubled star, has a weak and duskish fire, it would be meet that she should suffer none of these accidents which she is now seen to suffer, but altogether the contrary; to wit, that she should be seen when she is hidden, and absconded when she appears; that is, she should be concealed all the rest of the time, being obscured by the environing air, and again shine forth and become apparent and manifest for six months together, and afterwards disappear again five months, entering into the shadow of the earth. For of four hundred and sixty-five revolutions of ecliptic full moons, four hundred and four are of six months’ duration, and the rest of five. The moon then should all this time appear shining in the shadow; but on the contrary we see, that in the shadow she is eclipsed and loses her light, and recovers it again after she is escaped and got forth of the shadow. Nay, she appears often in the daytime, so that she is rather any thing else than a fiery and starry body.
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