§7Ὅτι δὲ διὰ τὴν τῆς ὄψεως κίνησιν ἰλιγγιᾶν συμβαίνει φανερὸν ἐκ πολλῶν.
That dizziness occurs because of the movement of sight is clear from many instances.
Οἵ τε γὰρ πλέοντες θᾶττον καὶ μᾶλλον ἰλιγγιῶσιν ὅταν ἐμβλέπωσι τοῖς κύμασι καὶ τῇ τῶν * ὅλων ἄστρων κινήσει, διὸ καὶ ἐγκαλύπτονται τοῦτʼ εὐλαβούμενοι· καὶ οἱ τὰς αἰώρας καὶ τοὺς τροχοὺς θεωροῦντες ἢ καὶ συμπεριφέροντες τὴν ὄψιν ταχὺ σκοτοῦνται·
For those who sail get dizzy faster and more violently when they look at the waves and the movement of the stars as a whole, which is why they also cover themselves to guard against this; and those who watch swings and wheels, or even turn their sight along with them, quickly experience darkness.
συμβαίνει γὰρ κινουμένην κύκλῳ τὴν ὄψιν κινεῖν τὰ ἐντὸς ἀνωμάλως καὶ ταράττειν.
For it happens that the sight, being moved in a circle, moves the inside irregularly and disturbs it.
§8Ἰλιγγιῶσι δὲ καὶ οἱ τὰ ὑψηλὰ καὶ τὰ μεγάλα καὶ ἀπότομα ἀποβλέποντες διὰ τὸ συμβαίνειν μακρὰν ἀποτεινομένην σείεσθαι καὶ κραδαίνεσθαι τὴν ὄψιν· σειομένη δὲ οὕτως καὶ κινουμένη ταράττει καὶ κινεῖ τὰ ἐντός.
And those who look down at high, large, and precipitous places also get dizzy, because it happens that the sight, stretching far out, is shaken and vibrated; and being shaken and moved in this way, it disturbs and moves the inside.
Ἀναβλέπουσι δʼ οὐ συμβαίνει τοῦτο διὰ τὸ μὴ ἀποτείνειν μακρὰν ἀλλʼ ἀποτέμνεσθαι ἐν τῷ φωτί.
But this does not happen to those who look up, because the sight does not stretch far but is cut short in the light.
§9Γίνεται δʼ ἴλιγγος καὶ ὅταν εἰς τὸ αὐτὸ βλέπωσι καὶ ἐπατενίζωσιν.
Dizziness also occurs when people look at the same spot and stare intently.
Ὃ καὶ ἐπαπορεῖται διὰ τί ποτε κινουμένης κύκλῳ τῆς ὄψεως καὶ ἠρεμούσης συμβαίνει τὸ αὐτὸ πάθος· ἄτοπον γὰρ τὸ ὑπʼ ἐναντίων.
This raises the further question of why the same condition occurs both when the sight is moving in a circle and when it is at rest; for it is strange that it should be caused by opposite things.
Αἴτιον δὲ τοῦ μὲν ἐν τῇ κυκλοφορίᾳ τὸ εἰρημένον, τοῦ δʼ ἐν τῇ ἐπιστάσει καὶ τῷ ἀτενισμῷ, διότι τὰ ἐν τῷ κινεῖσθαι σωζόμενα διίστησι καὶ ἡ στάσις· τῆς ὄψεως δὲ στάσης, ἑνὸς μοοίου, καὶ τἆλλα τὰ συνεχῆ ἐν τῷ ἐγκεφάλῳ ἵσταται· διιστάμενα δὲ καὶ χωριζόμενα τὰ βαρέα καταβαρύνει καὶ ποιεῖ τὸν ἴλιγγον.
The cause in the case of circular motion is what has been said, but in the case of fixing the gaze and staring, it is because even rest separates those things which are preserved while in motion; and when the sight, which is a single part, stops, the other continuous things in the brain also stop; and when the heavy things are separated and divided, they weigh down and cause dizziness.
Τὰ γὰρ πεφυκότα κινεῖσθαι τήνδε τὴν κίνησιν σώζεται καὶ συμμένει διὰ ταύτην· εἰ δὲ μὴ, καθάπερ Ἡράκλειτός φησι, καὶ ὁ κυκεὼν διίσταται μὴ κινούμενος.
For things that are naturally suited to move with this motion are preserved and remain together because of it; otherwise, as Heraclitus says, even the barley-drink separates if it is not stirred.
§10Εἴη δʼ ἂν καὶ τῇ κυκλοφορίᾳ αὐτὸ τοῦτʼ ἀποδιδόναι· διίστησι γὰρ ἡ δίνη τά τε βαρέα καὶ κοῦφα δέον ἅμα εἶναι τὰ μὲν εἰς τὸ μέσον ἄγουσα τὰ δʼ εἰς τὸ ἔσχατον.
And one might attribute this very same thing to circular motion as well; for the vortex separates the heavy and light things, which ought to be together, bringing the former to the center and the latter to the extremity.
Ποιεῖ δὲ καὶ τὸ κύπτειν ἰλίγγους διὰ τοῦτο· χωρίζεται γὰρ τὰ βαρέα καὶ ἐλαφρὰ, τὰ μὲν ἄνω τὰ δὲ κάτω· δεῖ δὲ ἅμα εἶναι καθάπερ ἐλέχθη.
Stooping also causes dizziness for this reason; for the heavy and light things are divided, the former upward and the latter downward, whereas they ought to be together as has been said.
§11Ποιεῖ δὲ καὶ ἄλλη τις ἐναντίωσις ὡς δοκεῖ, οἷον ἡ τῆς ἐνδείας καὶ σμονὴ περίττωσιν ἐποίησεν ὥστε πλήρεις γίνεσθαι τοὺς πόρους· ἀμφότερα γὰρ ταῦτα καταβαρύνει καὶ ἐφίστησι τὰς περιόδους, ὅπερ ἐστὶν ὁ ἴλιγγος· ἐπεὶ καὶ αἱ μέθαι καὶ αἱ φαρμακεῖαι καὶ ὅσα ἄλλα τούτοις παραπλήσια διὰ τοῦτο ποιεῖ τοὺς ἰλίγγους.
And another opposition, as it seems, also causes it, such as when deficiency and fullness produce a residue, so that the passages become full; for both of these weigh down and stop the revolutions, which is what dizziness is; since drunkenness, taking of drugs, and all other such things cause dizziness for this reason.
§12Ὅθεν καὶ τὸ σημεῖόν τινες ἐπʼ ἀμφοῖν κοινὸν λαμβάνουσιν· ὅταν γὰρ μὴ δύνηταί τις τοὺς στρωτῆρας ἢ τὰς δοκοὺς ἀριθμεῖν, τὸν μὲν οὔπω κεκαθάρθαι τὸν δὲ μεθύειν φασίν.
Hence some people take a common sign for both; for when someone cannot count the rafters or the beams, they say of the one that he is not yet purged, and of the other that he is drunk.
Ἡ ὑγρότης γὰρ ἡ ἀλλοτρία ἐμπεπτωκυῖα ποιεῖ τὴν ταραχήν· διὸ καὶ ἐφʼ ὅσων ἄλλων συμβαίνει πνεύματος ἢ ὑγρότητος γίνεσθαι πλῆθος ἢ καὶ τῶν ὑπαρχόντων διάστασιν ἀπὸ πάντων συμβαίνει τοῦτο τὸ πάθος.
For the alien moisture having fallen in produces the disturbance; wherefore in all other cases where a plenitude of breath or moisture occurs, or even a separation of the existing components, this condition arises from all of them.
§13Ἀνιστάμενοι δὲ μᾶλλον ἢ καθίζοντες ἰλιγγιῶσιν ὅτι ἠρεμούντων συνίσταται τὸ ὑγρὸν ἐν τῇ κεφαλῇ πλέον, ὅταν δὲ κινῶνται σφαλερὸν γίνεται καὶ εἰς ἓν μόριον ἀθρόον ἀποκλῖνον ποιεῖ τὸν ἴλιγγον.
And they get dizzy more when standing up than when sitting down, because when they are at rest, more moisture accumulates in the head, but when they move, it becomes unstable, and by inclining all at once to one part, it causes dizziness.