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to perceive in this way. But if this argument were true, the part being cut would not feel pain, but the brain would. It is better, therefore, to say that the nerve is brain. For it is a certain part of the brain, having the psychic pneuma throughout itself, as heated iron has fire; for this reason, wherever a sensory nerve is implanted, that part partakes of sensation from it and becomes sensory. And perhaps it is not absurd to say that not the sensation itself is sent up to the brain, the origin of the nerves, but a certain co-sensation and report of the sensation. The proper object of touch is the hot and the cold, the soft and the hard, the viscous and the brittle, the heavy and the light; for these are known by touch alone. But common to touch and sight are the sharp and the blunt, the rough and the smooth, the dry and the wet, the thick and the thin, up and down; and indeed place, and size when it is such as to be encompassed by a single application of touch, and the dense and the rare, and the round, when it is small, as well as certain other shapes. Likewise it also perceives the motion of a body approaching it, together with memory and thought. In the same way also of number; but only up to two or three, and these small and easily encompassed; but sight perceives these things better than touch, as also the even and the uneven. For it is of the genus of smooth and rough; for unevenness mixed with hardness produces roughness, while evenness with density produces smoothness. It is clear, therefore, from what has been said, that these senses have much in common with each other. For the one clarifies the errors of the other. In the case of a painting, for example, sight sees certain protrusions of the nose and of other things; but touch, on approaching, refutes its error. And just as sight always and everywhere sees through the medium of the air, so also touch perceives hard and soft and wet things through the medium of a staff, but syllogistically and with thought; for man has this sense in its most accurate form. In this, at any rate, and in taste he is superior to the other animals, although he is inferior in the other three. For one animal surpasses man in one of the three senses, another in another; but the dog in all three at once; for it hears and sees and smells more acutely, as is clear from tracking dogs. And the whole body is the organ of touch, as was said before; but especially the inner parts of the hands, and of these even more the tips of the fingers; for we have these as if they were accurate gauges of touch. For the creator fashioned the hands not only as an organ for grasping but also for touching. For this reason they have thinner skin, and muscle is laid under their whole inner surface, and they are devoid of hair, so that they may better perceive tangible things. And the underlying muscle has been the cause of their not growing hair. Of the hands, the harder ones are stronger for grasping, but the softer ones are more accurate for touching; just as also of the nerves, the hard ones are more suited for motion, but the soft ones for sensation. For these themselves are the organs of touch; for through them the sensation of touch occurs. 9 Concerning taste We said in the foregoing that sight sees in straight lines; but smell and hearing not only in a straight line but from all directions. But touch and taste perceive neither in straight lines nor from all directions, but only when they approach their proper objects, except for what has already been determined. Taste is perceptive of flavors. Its organs are the tongue, and of this especially the tip, and in addition to these the palate, in which are the flattened nerves carried from the brain, reporting the perception that has occurred to the governing faculty. Of flavors, the so-called gustatory qualities are these: sweetness, sourness, pungency, astringency, harshness, bitterness, saltiness, richness. For taste is discriminative of these. And according to these qualities, water is said to be without quality, because it exhibits none of these qualities in taste.

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οὕτως αἰσθάνεσθαι. ἀλλ' εἴπερ ἦν ἀληθὴς οὗτος ὁ λόγος οὐκ ἂν ἤλγει τὸ τεμνόμενον μόριον ἀλλ' ὁ ἐγκέφαλος. βέλτιον οὖν λέγειν ὅτι τὸ νεῦρον ἐγκέφαλός ἐστιν. καὶ γὰρ μοῖρά τις ἐστὶν ἐγκεφάλου, διὰ παντὸς ἑαυτοῦ τὸ ψυχικὸν ἔχον πνεῦμα, ὡς ὁ πεπυρακτω μένος σίδηρος ἔχει τὸ πῦρ· διά τοι τοῦτο ἔνθα ἂν νεῦρον αἰσθητικὸν ἐμφύηται ἐκεῖνο τὸ μέρος αἰσθήσεως ὑπ' αὐτοῦ μεταλαμβάνει καὶ γίνεται αἰσθητικόν. οὐδὲν δὲ ἴσως ἄτοπον λέγειν ἐπὶ τὴν ἀρχὴν τῶν νεύρων τὸν ἐγκέφαλον ἀναπέμπεσθαι οὐ τὸ πάθος ἀλλὰ συναίσθησίν τινα καὶ ἀπαγγελίαν τοῦ πάθους. ἔστι δὲ ἴδιον αἰσθητὸν ἁφῆς τὸ θερμὸν καὶ ψυχρόν, τό τε μαλακὸν καὶ σκληρόν, καὶ γλίσχρον καὶ κραῦρον, βαρύ τε καὶ κοῦφον· διὰ μόνης γὰρ τῆς ἁφῆς ταῦτα γνωρίζεται. κοινὰ δὲ ἁφῆς καὶ ὄψεως τό τε ὀξὺ καὶ ἀμβλὺ καὶ τὸ τραχὺ καὶ λεῖον, τό τε ξηρὸν καὶ ὑγρόν, παχύ τε καὶ λεπτόν, ἄνω καὶ κάτω· καὶ γὰρ ὁ τόπος, τό τε μέγεθος ὅταν ᾖ τοιοῦτον ὡς κατὰ μίαν προσβολὴν τῆς ἁφῆς περιλαμβάνεσθαι, καὶ τὸ πυκνὸν δὲ καὶ τὸ μανὸν καὶ τὸ στρογγύλον, ὅταν ᾖ μικρόν, ὡς καὶ ἄλλα τινὰ σχήματα. ὁμοίως δὲ καὶ τῆς κινήσεως τοῦ πλησιάζοντος αὐτῇ σώματος αἰσθάνεται σὺν τῇ μνήμῃ καὶ τῇ διανοίᾳ. ὡσαύτως δὲ καὶ ἀριθμοῦ· ἀλλὰ μέχρι δυοῖν ἢ τριῶν καὶ τούτων μικρῶν καὶ ῥᾳδίως περιλαμβανομένων· μᾶλλον δὲ τῆς ἁφῆς ἡ ὄψις τούτων ἀντιλαμβάνεται, ὥσπερ καὶ τοῦ ὁμαλοῦ καὶ τοῦ ἀνωμάλου. τοῦ γὰρ γένους ἐστὶ τοῦ λείου καὶ τραχέος σκληρότητι μὲν γὰρ ἀνωμαλία μιχθεῖσα τραχύτητα, ὁμαλότης δὲ πυκνότητι λειότητα ποιεῖ. δῆλον οὖν ἐκ τῶν εἰρημένων ὡς πολλὴν κοινωνίαν αἱ αἰσθήσεις αὗται πρὸς ἀλλήλας ἔχουσι. καὶ γὰρ τὰ τῆς ἑτέρας διαμαρτήματα ἡ ἑτέρα διασαφεῖ. ἐπὶ γοῦν τῆς γραφῆς ἡ μὲν ὄψις ἐξοχάς τινας ὁρᾷ ῥινός τε καὶ τῶν ἄλλων· ἡ δὲ ἁφὴ προσελθοῦσα διήλεγξεν αὐτῆς τὸ διαμάρτημα. ὥσπερ δὲ ἡ ὄψις ἀεὶ καὶ πάντα διὰ μέσου τοῦ ἀέρος ὁρᾷ, οὕτω καὶ ἡ ἁφὴ διὰ μέσης τῆς βακτηρίας τῶν σκληρῶν καὶ μαλακῶν καὶ ὑγρῶν αἰσθάνεται, ἀλλὰ συλλογιστικῶς καὶ μετὰ διανοίας· ἀκριβεστάτην γὰρ ἔχει ταύτην τὴν αἴσθησιν ὁ ἄνθρωπος. ταύτῃ γοῦν καὶ τῇ γεύσει πλέον ἔχει τῶν ἄλλων ζῴων, καίτοι ταῖς ἄλλαις τρισὶν ἡττώμενος. ἄλλο μὲν γὰρ ζῷον κατ' ἄλλην αἴσθησιν τῶν τριῶν πλεονεκτεῖ τὸν ἄνθρωπον· ὁ δὲ κύων ἐν ταῖς τρισὶν ἅμα· ὀξύτερον γὰρ καὶ ἀκούει καὶ βλέπει καὶ ὀσφραίνεται, ὡς δῆλον ἐκ τῶν ἰχνευόντων κυνῶν. καὶ πᾶν μὲν τὸ σῶμα τῆς ἁφῆς ἐστιν αἰσθητήριον, ὡς καὶ πρόσθεν εἴρηται· μάλιστα δὲ τῶν χειρῶν τὰ ἔσωθεν, καὶ τούτων ἔτι μᾶλλον τὰ ἄκρα τῶν δακτύλων· ταῦτα γὰρ ὥσπερ γνώμονας ἀκριβεῖς τῆς ἁφῆς ἔχομεν. οὐ γὰρ μόνον ἀντιληπτικὸν ὄργανον ὁ δημιουργὸς τὰς χεῖρας κατεσκεύασεν ἀλλὰ καὶ ἁπτικόν. διὰ τοῦτο καὶ τὸ δέρμα λεπτότερον ἔχουσι καὶ μῦς αὐταῖς ὅλαις ἔσωθεν ὑπέστρωται καὶ τριχῶν ἀμοιροῦσιν, ἵνα μᾶλλον τῶν ἁπτῶν ἀντιλαμβάνωνται. τοῦ δὲ τρίχας αὐτὰς μὴ φύειν ὁ ὑπεστορεσμένος μῦς γέγονεν αἴτιος. τῶν δὲ χειρῶν αἱ μὲν σκληρότεραι πρὸς ἀντίληψίν εἰσιν ἰσχυρότεραι· αἱ δὲ μαλακώτεραι πρὸς τὴν ἁφὴν ἀκριβέστεραι· ὥσπερ καὶ τῶν νεύρων τὰ μὲν σκληρὰ πρὸς κίνησιν, τὰ δὲ μαλακὰ πρὸς αἴσθησίν εἰσιν ἐπιτηδειότερα. ταῦτα γὰρ αὐτὰ τῆς ἁφῆς ἐστιν ὄργανα· διὰ τούτων γὰρ ἡ τῆς ἁφῆς αἴσθησις γίνεται. 9 περὶ γεύσεωσ Τὴν μὲν ὄψιν ἐν τοῖς ἔμπροσθεν εἴπομεν κατ' εὐθείας γραμμὰς ὁρᾶν· ἡ δὲ ὄσφρησις καὶ ἡ ἀκοὴ οὐ κατ' εὐθεῖαν μόνον ἀλλὰ πανταχόθεν. ἁφὴ δὲ καὶ γεῦσις οὔτε κατ' εὐθείας γραμμὰς οὔτε πανταχόθεν γνωρίζουσιν· ἀλλὰ τότε μόνον ὅταν αὐτοῖς πλησιάσωσιν τοῖς ἰδίοις αἰσθητοῖς, πλὴν τῶν ἤδη διωρισμένων. ἔστιν δὲ ἡ γεῦσις τῶν χυμῶν ἀντιληπτική· ὄργανα δὲ αὐτῆς ἡ γλῶσσα, καὶ ταύτης μᾶλλον τὸ ἄκρον, ἔτι τε σὺν τούτοις ἡ ὑπερῷα, ἐν οἷς ἔστι τὰ ἐξ ἐγκεφάλου φερόμενα νεῦρα πεπλατυσμένα καὶ ἀπαγγέλλοντα τὴν γενομένην ἀντίληψιν πρὸς τὸ ἡγεμονικόν. τῶν δὲ χυμῶν αἱ γευστικαὶ καλούμεναι ποιότητές εἰσιν αὗται· γλυκύτης ὀξύτης δριμύτης στρυφνότης αὐστηρότης πικρότης ἁλμυρότης λιπαρότης. τούτων γάρ ἐστιν ἡ γεῦσις διαγνωστική. κατὰ ταύτας δὲ τὰς ποιότητας καὶ τὸ ὕδωρ ἄποιον λέγεται, τῷ μηδεμίαν τούτων ἐμφαίνειν ἐν τῇ γεύσει ποιότητα.