§31.1Διὰ τί τρίψαντες τὸν ὀφθαλμὸν παυόμεθα τῶν πταρμῶν;
Why, when we rub the eye, do we stop sneezing?
ἢ ὅτι ἀναπνοὴ ταύτῃ γίνεται τῷ ὑγρῷ;
Is it because an outlet is thus produced for the moisture?
δακρύει γὰρ ὁ ὀφθαλμὸς μετὰ τὴν τρῖψιν· ὁ δὲ πταρμὸς διὰ πλῆθος ὑγροῦ.
For the eye waters after the rubbing; and sneezing is due to an abundance of moisture.
ἢ ὅτι τὸ ἔλαττον θερμὸν φθείρεται ὑπὸ τοῦ πλείονος;
Or is it because the lesser heat is destroyed by the greater?
ὁ δὲ ὀφθαλμὸς τριφθεὶς πλείω λαμβάνει θερμότητα τῆς ἐν τῇ ῥινί.
And the rubbed eye receives a greater heat than that in the nose.
διὰ τοῦτο δὲ κἄν τις αὐτὴν τὴν ῥῖνα τρίψῃ, παύεται ὁ πταρμός.
For this reason, even if one rubs the nose itself, the sneezing stops.
§31.2Διὰ τί τῷ ἑνὶ ὀφθαλμῷ ἀκριβέστερον ὁρῶσιν ἢ τοῖν δυοῖν;
Why do people see more accurately with one eye than with both?
ἢ ὅτι πλείους οὖσαι κινήσεις τοῖν δυοῖν γίνονται, οἷον τοῖς διεστραμμένοις;
Is it because, in the case of both eyes, the movements that occur are more numerous, as with squinting people?
οὔκουν μία ἡ κίνησις, τοῦ δὲ ἑνὸς ἁπλῆ.
Therefore the movement is not one, whereas that of the single eye is simple.
ἧττον οὖν ὁρῶσιν ἀκριβέστερον.
They therefore see less accurately.
§31.3Διὰ τί ὀργιζόμενοι μὲν τοὺς ὀφθαλμοὺς μάλιστα ἐπιδιδόασι πρὸς τὸ ἐρυθριᾶν, αἰσχυνόμενοι δὲ τὰ ὦτα ἢ διότι οἱ μὲν καταψύχονται ἐν τῇ αἰδοῖ (ἐν ὀφθαλμοῖς γὰρ αἰδώς) ἀντιβλέπειν οὐ δύνανται;
Why is it that when people are angry, they chiefly show redness in their eyes, but when they are ashamed, in their ears?
καὶ ἡ δειλία κατάψυξίς τίς ἐστιν ἐνταῦθα.
Is it because in shame the eyes are cooled (for shame is in the eyes) and they cannot look in the face?
μεθίσταται δὲ εἰς τοὐναντίον τῷ ἔμπροσθεν τὸ ὄπισθεν.
And cowardice is a kind of cooling in that region.
τὰ δὲ ὦτα ἀντίκειται· διὸ καὶ μάλιστα ἐρυθριῶσιν αἰσχυνόμενοι.
But the back parts change to the opposite of the front parts.
ἐν δὲ τῷ κνήθεσθαι ἐπὶ τὸ αἰσθητικώτερον καὶ κινητικώτερον ἡ βοήθεια ὡς ἀδικουμένου· φοβουμένοις γὰρ ἐνταῦθα ἐκλείπει μάλιστα.
And the ears are opposite; therefore they especially turn red when people are ashamed.
§31.4Διὰ τί θατέρου καταληφθέντος ὀφθαλμοῦ ὁ ἕτερος ἀτενίζει μᾶλλον;
But in being tickled, help comes to the part that is more sensitive and easily moved, as if it were wronged; for in those who fear, heat especially fails in that part.
ἢ διότι ἐκ ταὐτοῦ ἤρτηνται αἱ ἀρχαὶ τῶν ὀφθαλμῶν;
Why is it that when one eye is closed, the other gazes more intently?
θατέρου οὖν κινουμένου καὶ ἡ κοινὴ ἀρχὴ κινεῖται, ἐκείνης δὲ κινουμένης καὶ ὁ ἕτερος.
Is it because the origins of the eyes are suspended from the same place?
ληφθέντος οὖν θατέρου ἡ κίνησις κινήσει αὐτόν, ὥστε δύναται ἀτενίζειν μᾶλλον.
Therefore, when one moves, the common origin also moves, and when that moves, the other eye also moves.
§31.5Διὰ τί οἱ ἐκ γενετῆς τυφλοὶ οὐ γίνονται φαλακροί;
Therefore, when one is closed, the motion will move the other, so that it is able to gaze more intently.
ἢ ὅτι πημαίνει τὰ ὄμματα ὑγρότης οὖσα πολλὴ ἐν τῷ περὶ τὴν κεφαλὴν τόπῳ;
Why do those who are blind from birth not become bald?
διὸ τῶν ῥευματικῶν εἰς τοὺς ὀφθαλμοὺς τάς τε περὶ τοὺς κροτάφους φλέβας κάουσι, πυκνοῦντες τοὺς τῶν ὑγρῶν πόρους, καὶ ξύουσι τὴν κεφαλήν, διατέμνοντες τὸ ἐν αὐτῇ δέρμα.
Is it because the moisture, being abundant in the region of the head, damages the eyes?
ἐπεὶ οὖν πημαίνει τοὺς ὀφθαλμοὺς τὸ ἐν αὐτῇ περίττωμα γινόμενον, κωλύοι ἂν αὑτοὺς ταὐτὸ τοῦτο ἐξ ἀρχῆς γίνεσθαι, πλέον συνιστάμενον ἐν αὐτῇ.
Therefore, in those who suffer from defluxions into the eyes, they cauterize the veins around the temples, condensing the passages of the moistures, and scrape the head, cutting through the skin on it.
ἐπεὶ δὲ ἐκ περιττωμάτων θρὶξ φύεται, τοῦτο δὲ ἐν τῇ τῶν τυφλῶν κεφαλῇ ἐκ γενετῆς ἐστὶ πολύ, εἰκότως οὐκ εἰσὶ φαλακροί.
Since, then, the residue arising in the head damages the eyes, this very thing, being collected in greater quantity in it, would prevent them from coming into being from the beginning.
§31.6Διὰ τί οἱ ἐξόφθαλμοι καπνίζονται μᾶλλον;
And since hair grows from residues, and this is abundant from birth in the head of the blind, they are naturally not bald.
ἢ ὅτι τάχιστα προσπίπτει προέχοντα;
Why are those with prominent eyes more affected by smoke?
§31.7Διὰ τί εἰς μὲν τὰ δεξιὰ ἀμφοτέρας τὰς ὄψεις ἅμα διαστρέφειν δυνάμεθα, καὶ εἰς τὰ ἀριστερὰ καὶ πρὸς τὴν ῥῖνα, καὶ εἰς τὸ ἀριστερὸν δὲ ἢ τὸ δεξιὸν τὴν ἑτέραν, ἅμα δὲ εἰς τὸ δεξιὸν καὶ ἀριστερὸν ἀδυνατοῦμεν; ὁμοίως δὲ καὶ εἰς τὸ κάτω καὶ εἰς τὸ ἄνω·
Is it because, since they project, the smoke falls upon them most quickly?
ἅμα μὲν γὰρ ἐπὶ ταὐτὸ δυνάμεθα, χωρὶς δὲ οὔ.
Why is it that we can turn both eyes together to the right, and to the left, and towards the nose, and one of them to the left or to the right, but we cannot turn them together to the right and left?
ἢ ὅτι αἱ ὄψεις δύο οὖσαι ὅμως ἐξ ἑνὸς συνήρτηνται;
And similarly also downwards and upwards; for we can turn them together to the same point, but not separately.
ὅσα δὲ τοιαῦτα, ἄκρου θατέρου κινουμένου ἀνάγκη θάτερον ἀκολουθεῖν ἐπὶ ταὐτό.
Is it because the eyes, though being two, are nevertheless joined from a single source?
τῷ γὰρ ἑτέρῳ ἄκρῳ ἡ ἀρχὴ θάτερον ἄκρον.
In all such things, when one extremity is moved, the other must necessarily follow in the same direction.
εἰ οὖν τὸ ἓν ἀδύνατον ἅμα εἰς τἀναντία κινεῖσθαι, ἀδύνατον καὶ τὰς ὄψεις.
For to the one extremity, the origin is the other extremity.
τὰ μὲν γὰρ ἄκρα εἰς τἀναντία ἂν κινοῖτο, εἰ τὸ μὲν ἄνω τὸ δὲ κάτω κινοῖτο, ἡ δὲ ἀρχὴ ἀμφοῖν ἂν ἀκολουθοίη, ὅπερ ἀδύνατον.
If, therefore, it is impossible for a single thing to move in opposite directions at the same time, it is also impossible for the eyes.
ἡ δὲ διαστροφή ἐστι τῶν ὀμμάτων διὰ τὸ ἀρχὴν ἔχειν τὰς σφαίρας, καὶ μέχρι τοῦ στρέφεσθαι εἰς τὰ ἄνω καὶ κάτω καὶ εἰς πλάγιον.
For the extremities would move in opposite directions, if the one were to move upwards and the other downwards, and the origin would have to follow both, which is impossible.
ὅταν οὖν ἔχουσαι ὡς ἂν ὁμοίως ἔχοιεν τῇ θέσει ἀλλήλαις, καὶ ἐν μέσῳ τοῦ ἐπὶ τὸ ἄνω καὶ κάτω κινεῖσθαι, καὶ εἰς πλάγιον ἐπὶ τοῦ αὐτοῦ σημείου ἑαυτῶν λάβωσιν τὴν ὄψιν, αὗται μὲν ἀδιάστροφοί τε καὶ μάλιστα ἀκίνητοι τῇ θέσει·
And squinting occurs because the spheres have a starting point even up to their turning upwards, downwards, and sideways.
ὅσαι δὲ ἐπὶ ταὐτοῦ σημείου λάβωσι τὰς ὄψεις, ἀδιάστροφοι μέν εἰσι, διαφέρουσι δὲ ἀλλήλων.
When, therefore, while being situated similarly to one another in position, and in the middle of moving upwards, downwards, and sideways, they focus their sight on the same point of themselves, these eyes are undistorted and most stable in position.
καίτοι κρύπτεται τοῦ μέλανός τι καὶ τοῖς ἄνω βάλλουσι τὰ λευκά, οἷον μελλέπταρμοι·
And all those eyes which focus their sights on the same point are indeed undistorted, but they differ from one another.
ἕτεροι δὲ εἰς τὸ πλάγιον, ὥσπερ οἱ μανικοί, οἱ δὲ εἰς τοὺς μυκτῆρας, ὥσπερ τὰ τραγικὰ πρόσωπα καὶ οἱ στρυφνοί σύννουν γὰρ τὸ βλέμμα.
Indeed, some part of the black is hidden even in those who cast their whites upwards, like those about to sneeze; and others sideways, like madmen, and others towards the nostrils, like tragic masks and sour-tempered people; for their gaze is thoughtful.
ὅσοι δὲ μήθ’ ὑμοίως κειμένων τῶν σφαιρῶν ἐπὶ ταὐτῷ σημείῳ ἔχουσι τὰς ὄψεις, ἢ ὁμοίως μὲν κειμένων, μὴ ἐπὶ τῷ αὐτῷ δέ, οὗτοι διεστραμμένοι εἰσίν· διὸ ὑποβλέπουσι καὶ συνάγουσι τὰ ὄμματα.
But those who, when the spheres are not similarly situated, focus their sights on the same point, or when they are similarly situated, not on the same point, these are squinting; therefore they look askance and bring their eyes together.
πειρῶνται γὰρ ἐπὶ ταὐτὸν καταστῆσαι σχῆμα τὴν σφαῖραν.
For they try to bring the sphere to the same configuration.
ὥστε τὸν μὲν ἐῶσι, τὸν δὲ σχηματίζουσι τῶν ὀφθαλμῶν.
Consequently, they leave one of the eyes alone, and shape the other.
ἐὰν γὰρ μὴ κατ’ αὐτὸ σημεῖον τεθῶσιν αἱ ὄψεις, ἀνάγκη διεστράφθαι.
For unless the sights are placed at the very same point, they must necessarily be distorted.
ὥσπερ γὰρ τοῖς ὑποβάλλλουσιν ὑπὸ τὸν ὀφθαλμὸν [τὸ ἓν] δύο φαίνεται (καὶ γὰρ ἐκείνοις κεκίνηται ἡ ἀρχή), καὶ τούτοις ὁμοίως.
For just as to those who press under their eye, one thing appears as two (for in their case also the origin has been moved), so it is similarly with these.
ἐὰν μὲν οὖν ἄνω κινηθῇ ὁ ὀφθαλμός, τὸ πέρας κάτω τῆς ὄψεως γίνεται, ἐὰν δὲ κάτω, ἄνω τὸ πέρας.
If, then, the eye moves upwards, the limit of the sight becomes downwards; and if downwards, the limit becomes upwards.
ἐν ἑνὶ δὲ ὀφθαλμῷ μεθισταμένῳ κινεῖσθαι μὲν τὸ ὁρώμενον δοκεῖ διὰ ταῦτα ἄνω ἢ κάτω, ὅτι καὶ ἡ ὄψις, δύο δὲ οὐ φαίνεται, ἂν μὴ δύο αἱ ὄψεις ὦσιν, καὶ διαστρέφει.
And when one eye is shifted, the object seen indeed appears to move upwards or downwards for this reason, because the sight also does so, but it does not appear as two, unless there are two sights and it squints.
τοιαύτη μὲν τῷ ἑτεροφθάλμῳ γίνεται, ὥστε δύο φαίνεσθαι· κατὰ τὴν θέσιν δὲ γίνεται τῷ μὴ κατὰ μέσον τοῦ ὄμματος κεῖσθαι.
Such a condition occurs in a squint-eyed person, so that things appear as two; and it happens in respect of position because the sight is not situated in the middle of the eye.