LCL 288: 216-217
436 a οἷόν τε γίνεσθαι τοῖς ἐστερημένοις ζωῆς. διὸ 20σχεδὸν τῶν τε περὶ φύσεως οἱ πλεῖστοι καὶ τῶν ἰατρῶν οἱ φιλοσοφωτέρως τὴν τέχνην μετιόντες, 436 bοἱ μὲν τελευτῶσιν εἰς τὰ περὶ ἰατρικῆς, οἱ δ᾿ ἐκ τῶν περὶ φύσεως ἄρχονται περὶ τῆς ἰατρικῆς.
Ὅτι δὲ τὰ λεχθέντα κοινὰ τῆς τε ψυχῆς ἐστὶ καὶ τοῦ σώματος, οὐκ ἄδηλον. πάντα γὰρ τὰ μὲν μετ᾿ αἰσθήσεως συμβαίνει, τὰ δὲ δι᾿ αἰσθήσεως· 5ἔνια δὲ τὰ μὲν πάθη ταύτης ὄντα τυγχάνει, τὰ δ᾿ ἕξεις, τὰ δὲ φυλακαὶ καὶ σωτηρίαι, τὰ δὲ φθοραὶ καὶ στερήσεις. ἡ δ᾿ αἴσθησις ὅτι διὰ σώματος γίνεται τῇ ψυχῇ, δῆλον καὶ διὰ τοῦ λόγου καὶ τοῦ λόγου χωρίς.
Ἀλλὰ περὶ μὲν αἰσθήσεως καὶ τοῦ αἰσθάνεσθαι, τί ἐστι καὶ διὰ τί συμβαίνει τοῖς ζῴοις τοῦτο τὸ 10πάθος, εἴρηται πρότερον ἐν τοῖς περὶ ψυχῆς. τοῖς δὲ ζῴοις, ᾗ μὲν ζῷον ἕκαστον, ἀνάγκη ὑπάρχειν αἴσθησιν· τούτῳ γὰρ τὸ ζῷον εἶναι καὶ μὴ ζῷον διορίζομεν. ἰδίᾳ δ᾿ ἤδη καθ᾿ ἕκαστον ἡ μὲν ἁφὴ καὶ γεῦσις ἀκολουθεῖ πᾶσιν ἐξ ἀνάγκης, ἡ μὲν 15ἁφὴ διὰ τὴν εἰρημένην αἰτίαν ἐν τοῖς περὶ ψυχῆς, ἡ δὲ γεῦσις διὰ τὴν τροφήν· τὸ γὰρ ἡδὺ διακρίνει καὶ τὸ λυπηρὸν αὕτη περὶ τὴν τροφήν, ὥστε τὸ μὲν φεύγειν τὸ δὲ διώκειν, καὶ ὅλως ὁ χυμός ἐστι τοῦ θρεπτικοῦ μορίου πάθος. αἱ δὲ διὰ τῶν ἔξωθεν αἰσθήσεις τοῖς πορευτικοῖς αὐτῶν, οἷον ὄσφρησις 20καὶ ἀκοὴ καὶ ὄψις, πᾶσι μὲν τοῖς ἔχουσι σωτηρίας ἕνεκεν ὑπάρχουσιν, ὅπως διώκωσί τε προαισθανόμενα τὴν τροφὴν καὶ τὰ φαῦλα καὶ τὰ φθαρτικὰ
things deprived of life. Hence one may say that most natural philosophers, and those physicians who take a scientific interest in their art, have this in common: the former end by studying medicine, and the latter base their medical theories on the principles of natural science.
It is obvious that the characteristics already mentionedConnexion of body and soul. belong to both soul and body. For all of them either appear in conjunction with sensation or arise through sensation: some again are affections of sensations and some are positive states; some again tend to guard and preserve life, and others to destroy and extinguish it. That sensation is produced in the soul through the medium of the body is obvious on theoretical grounds and also apart from theory.
Now we have already explained, in our work OnSensation is essential to the living creature. the Soul,a what sensation and sentience are, and why this affection appears among animals. Every animal qua animal must have sensation. For it is by this that we differentiate between what is and what is not an animal. As for the various individual senses, touch and taste are necessarily present in all animals, touch for the reason given in our work On the Soul,b and taste on account of nutrition; for it is taste which discriminates between pleasant and unpleasant in food, so that the one is avoided and the other pursued; and speaking generally flavour is an affection of the nutritive element. But those senses which act through external media, such as smell, hearing and vision, belong to such animals as are capable of locomotion. To all those which possess them they are a means of preservation, in order that they may be aware of their food before they pursue it, and may avoid what is inferior or destructive, while in those