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perception of sensible things. But Plato says sensation is a communion of soul and body towards external things. for the power is of the soul; but the instrument is of the body; but both are perceptive of external things through imagination. Of the psychic faculties, some are subservient and satellite-like; but others are ruling and governing. The ruling ones are the intellectual and the scientific; the subservient are the faculties of sense and motion according to impulse and the faculty of voice. For both motion and voice obey the will of reason most sharply and almost without time; for at the same and one time we both will and are moved, needing no intervening time between the will and the motion, as can be seen in the motion of the fingers; and some of the natural faculties are also under the governance of the intellectual, such as the so-called passions. 7 On vision Vision is spoken of homonymously; for both the sense-organ and the sensory power. But Hipparchus says that rays extending from the eyes, with their own extremities, just like the touch of hands, grasping external bodies, transmit the perception of them to the visual faculty. And the geometers describe certain cones arising from the convergence of the rays emitted through the eyes. For the right eye sends rays to the left, and the left eye to the right; and from their convergence a cone is formed, whence vision encompasses many visible things at once, but sees accurately those things where the rays converge. Thus, at any rate, often when we look at the ground we do not see the coin lying on it, gazing for a very long time, until the intersections of the rays occur in that part where the coin lies, and then we fall upon the sight of it, as if then for the first time we began to pay attention. The Epicureans say that images of the things that appear fall upon the eyes. But Aristotle says not a corporeal image but a quality arrives from visible things all the way to the vision through the alteration of the surrounding air. But Plato says by a coalescence of the light from the eyes flowing out to a certain distance into the kindred air, and of the light borne in the opposite direction from bodies, and of the intervening air, being easily diffused and pliable, being extended together with the fiery nature of vision. And Galen, in agreement with Plato concerning vision in the seventh book of the *Symphonia*, speaks, writing thus sporadically: for if some part or power or image or quality of the bodies seen arrived at the eye, we would not know the size of what is seen, for instance if it happened to be a very great mountain. For it is utterly irrational for such a large image to fall into our eyes; but indeed the optic pneuma is not able to take on so much strength when secreted as to be poured around all that is seen; it remains, therefore, that the surrounding air becomes such an instrument for us during the time we see, of the same kind as the optic nerve is in the body. For the air surrounding us seems to be affected in some such way; for the light of the sun, touching the upper limit of the air, transmits its power throughout the whole; and the light carried through the optic nerves has a pneumatic substance, and falling upon the surrounding medium and working the alteration on first contact, transmits it to a very great distance continuously with itself, until it falls upon a resistant body. For the air becomes an instrument for the eye for the discernment of visible things, of the same kind as the nerve is for the brain; so that the eye has the same relation to the air, which has been ensouled by the sun's light, as the brain has to the nerve. That the air is by nature assimilated to bodies approaching it is clear from the fact that, when there is light, if something fiery red or dark blue or even bright silver is carried through, the air is altered by what was carried through. But Porphyry in his *On Sensation* says that neither a cone nor an image nor anything else is the cause of seeing, but the soul itself, encountering the visible objects, recognizes itself as being the visible objects, because the soul contains all beings and all things are soul containing different bodies. for wanting to be one

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ἀντιλήψεως τῶν αἰσθητῶν. Πλάτων δὲ τὴν αἴσθησιν λέγει ψυχῆς καὶ σώματος κοινωνίαν πρὸς τὰ ἐκτός. ἡ γὰρ δύναμις ψυχῆς· τὸ δὲ ὄργανον σώματος· ἄμφω δὲ διὰ φαντασίας ἀντιληπτικὰ τῶν ἔξωθεν. τῶν δὲ ψυχικῶν τὰ μέν ἐστιν ὑπουργικά τε καὶ δορυφορικά· τὰ δὲ ἀρχικὰ καὶ ἡγεμονικά. ἀρχικὰ μὲν τό τε διανοητικὸν καὶ ἐπιστημονικόν· ὑπουργικὰ δὲ τά τε αἰσθητικὰ καὶ ἡ καθ' ὁρμὴν κίνησις καὶ τὸ φωνητικόν. καὶ γὰρ ἡ κίνησις καὶ ἡ φωνὴ ὀξύτατα καὶ σχεδὸν ἀχρόνως ὑπακούει τῇ βουλήσει τοῦ λογισμοῦ· ἅμα γὰρ καὶ κατὰ τὸ αὐτὸ θέλομέν τε καὶ κινούμεθα οὐδενὸς ἐπιδεόμενοι μεταξὺ χρόνου τῆς τε βουλήσεως καὶ τῆς κινήσεως, ὡς ἐπὶ τῆς κινήσεως τῶν δακτύλων ἐστὶν ἰδεῖν· καὶ τῶν φυσικῶν δὲ ἔνια ὑπὸ τὴν ἡγεμονίαν ἐστὶ τοῦ διανοητικοῦ, ὡς τὰ καλούμενα πάθη. 7 περὶ ὄψεωσ Ἡ ὄψις ὁμωνύμως λέγεται· καὶ γὰρ τὸ αἰσθητήριον καὶ ἡ δύναμις ἡ αἰσθητική. Ἵππαρχος δέ φησιν ἀκτῖνας ἀπὸ τῶν ὀφθαλμῶν ἀποτεινομένας τοῖς πέρασιν ἑαυτῶν καθάπερ χειρῶν ἐπαφαῖς καθαπτούσας τοῖς ἐκτὸς σώμασιν τὴν ἀντίληψιν αὐτῶν πρὸς τὸ ὁρατικὸν ἀναδιδόναι. οἱ δὲ γεωμέτραι κώνους τινὰς ἀναγράφουσιν ἐκ τῆς συνεμπτώσεως τῶν ἀκτίνων γινομένους τῶν ἐκπεμπομένων διὰ τῶν ὀφθαλμῶν. πέμπειν γὰρ ἀκτῖνας τὸν μὲν δεξιὸν ὀφθαλμὸν ἐπὶ τὰ ἀριστερά, τὸν δὲ ἀριστερὸν ἐπὶ τὰ δεξιά· ἀπὸ δὲ τῆς συνεμπτώσεως αὐτῶν ἀποτελεῖσθαι κῶνον, ὅθεν ὁμοῦ μὲν πολλὰ περιλαμβάνειν ὁρατὰ τὴν ὄψιν, βλέπειν δὲ ἀκριβῶς ἐκεῖνα ἔνθα ἂν συνεμπέσωσιν αἱ ἀκτῖνες. οὕτω γοῦν πολλάκις ὁρῶντες εἰς τοὔδαφος οὐχ ὁρῶμεν τὸ ἐν αὐτῷ νόμισμα κείμενον, ἀτενίζοντες ἐπὶ πλεῖστον, ἕως ἂν αἱ συμβολαὶ τῶν ἀκτίνων ἐν ἐκείνῳ γένωνται τῷ μέρει ἔνθα κεῖται τὸ νόμισμα, καὶ τότε τῇ θέᾳ προσπίπτομεν αὐτοῦ, ὡς τότε πρῶτον ἀρξάμενοι προσέχειν. οἱ δὲ ἐπικούρειοι εἴδωλα τῶν φαινομένων προσπίπτειν τοῖς ὀφθαλμοῖς. Ἀριστοτέλης δὲ οὐκ εἴδωλον σωματικὸν ἀλλὰ ποιότητα δι' ἀλλοιώσεως τοῦ πέριξ ἀέρος ἀπὸ τῶν ὁρατῶν ἄχρι τῆς ὄψεως παραγίνεσθαι. Πλάτων δὲ κατὰ συναύγειαν τοῦ μὲν ἐκ τῶν ὀφθαλμῶν φωτὸς ἐπὶ ποσὸν ἀπορρέοντος εἰς τὸν ὁμογενῆ ἀέρα, τοῦ δὲ ἀπὸ μὲν τῶν σωμάτων ἀντιφερομένου, τοῦ δὲ περὶ τὸν μεταξὺ ἀέρα, εὐδιάχυτον ὄντα καὶ εὔτρεπτον, συνεκτεινομένου τῷ πυροειδεῖ τῆς ὄψεως. Γαληνὸς δὲ συμφώνως Πλάτωνι περὶ τῆς ὄψεως ἐν τῷ ἑβδόμῳ τῆς Συμφωνίας λέγει, γράφων οὕτω πως σποράδην· εἴπερ γὰρ εἰς τὸν ὀφθαλμὸν ἀφικνεῖτο μοῖρά τις ἢ δύναμις ἢ εἴδωλον ἢ ποιότης τῶν ὁρωμένων σωμάτων, οὐκ ἂν τοῦ βλεπομένου τὸ μέγεθος ἔγνωμεν, οἷον ὄρους εἰ τύχοι μεγίστου. τη λικοῦτον γὰρ εἴδωλον ἐμπίπτειν τοῖς ὀφθαλμοῖς ἡμῶν παν τάπασιν ἄλογον· ἀλλὰ μὴν καὶ τὸ πνεῦμα τὸ ὀπτικὸν οὐχ οἷόν τε τοσαύτην ἰσχὺν ἐκκρινόμενον λαμβάνειν ὡς περι χεῖσθαι παντὶ τῷ βλεπομένῳ· λείπεται οὖν τὸν πέριξ ἀέρα τοιοῦτον ὄργανον ἡμῖν γίγνεσθαι καθ' ὃν ὁρῶμεν χρό νον ὁποῖον ἐν τῷ σώματι τὸ νεῦρον ὑπάρχει τὸ ὀπτικόν. τοιοῦτον γάρ τι πάσχειν ἔοικεν ὁ περιέχων ἡμᾶς ἀήρ· ἥ τε γὰρ αὐγὴ τοῦ ἡλίου, ψαύουσα τοῦ ἄνω πέρατος τοῦ ἀέρος, διαδίδωσιν εἰς ὅλον τὴν δύναμιν· ἥ τε διὰ τῶν ὀπτικῶν νεύρων αὐγὴ φερομένη, τὴν μὲν οὐσίαν ἔχει πνευ ματικήν, ἐμπίπτουσα δὲ τῷ περιέχοντι καὶ τῇ πρώτῃ προσβολῇ τὴν ἀλλοίωσιν ἐργαζομένη, διαδίδωσιν ἄχρι πλεί στου συνεχοῦς ἑαυτῇ, ἄχρις ἂν εἰς ἀντιτυπὲς ἐμπέσῃ σῶμα. γίνεται γὰρ ὁ ἀὴρ ὄργανον τῷ ὀφθαλμῷ πρὸς τὴν τῶν ὁρωμένων διάγνωσιν τοιοῦτον οἷόν περ ἐγκεφάλῳ τὸ νεῦρον· ὥστε ὃν ἔχει λόγον ἐγκέφαλος πρὸς τὸ νεῦ ρον, τοιοῦτον ἔχειν τὸν ὀφθαλμὸν πρὸς τὸν ἀέρα ἐψυχω μένον ὑπὸ τῆς ἡλιακῆς αὐγῆς. ὅτι δὲ πέφυκεν ὁ ἀὴρ τοῖς πλησιάζουσι σώμασιν συνεξομοιοῦσθαι δῆλον ἐκ τοῦ καὶ πυρροῦ τινὸς ἢ κυανοῦ ἢ καὶ ἀργύρου λαμπροῦ διαφερομένου φωτὸς ὄντος ὑπὸ τοῦ διενεχθέντος ἀλλοιοῦσθαι τὸν ἀέρα. Πορφύριος δὲ ἐν τῷ Περὶ αἰσθήσεως οὔτε κῶνον οὔτε εἴδωλον οὔτε ἄλλο τί φησιν αἴτιον εἶναι τοῦ ὁρᾶν ἀλλὰ τὴν ψυχὴν αὐτὴν ἐντυγχάνουσαν τοῖς ὁρατοῖς ἐπιγινώσκειν ἑαυτὴν οὖσαν τὰ ὁρατὰ τῷ τὴν ψυχὴν συνέχειν πάντα τὰ ὄντα καὶ εἶναι τὰ πάντα ψυχὴν συνέχουσαν σώματα διάφορα. μίαν γὰρ βουλόμενος εἶναι