§2.10.77 ἔτι δὲ τὰς ἀκριβεστέρας τῶν αἰσθήσεων διὰ τῶν καθαρώτερον ἐχόντων τὸ αἷμα μορίων ἀναγκαῖον ἀκριβεστέρας γίνεσθαι· ἐκκύπτει γὰρ ἡ τῆς ἐν τῷ αἵματι θερμότητος κίνησις τὴν αἰσθητικὴν ἐνέργειαν·
7 Furthermore, more accurate sensations must necessarily become more accurate through those parts that have purer blood; for the movement of the heat in the blood hinders the sensory activity.
διὰ ταύτας τὰς αἰτίας ἐν τὴ κεφαλ ῇ τούτων τὰ αἰσθητήριά ἐστιν.
For these causes, the sense organs of these sensations are in the head.
οὐ μόνον δʼ ἐστὶ τὸ ἔμπροσθεν ἄσαρκον, ἀλλὰ τὸ ὄπισθεν της κεφαλῆς, διὰ τὸ πᾶσι τοῖς ἕχουσιν αὐτὴν ὀρθότατον δεῖν εἶναι τούτο τὸ μόριον· οὐδὲν γὰρ ὀρθοῦσθαι δύναται φορτίον ἔχον, ἢν δʼ ἂν τοιοὺτον, εί σεσαρκωμένην εἶχε τὴν κεφαλήν.
And not only is the front part fleshless, but also the back of the head, because this part must be the most upright in all animals that have it; for nothing is able to stand upright if it has a burden, and it would be such a burden if it had a fleshy head.
ᾖ καὶ δῆλον ὅτι οὐ τῆς τού ἐγκεφάλου αἰσθήσεως χάριν ἄσαρκος ἡ κεφαλή ἐστιν· τὸ γὰρ ὄπισθεν οὐκ ἔχει ἐγκέφαλον, ἄσαρκον δʼ ὁμοίως.
Whereby it is also clear that the head is not fleshless for the sake of the brain's sensation; for the back part does not have a brain, yet is likewise fleshless.
§2.10.88 ἔχει δὲ καὶ τὴν ἀκοὴν εὐλόγως ἔυια τῶν ζῷόων ἐν τῷ τόπῳ τῷ περὶ τὴν κεφαλήν· τὸ γὰρ κενὸν καλούμενον ἀέρος πλῆρές ἐστι, τὸ δὲ τὴς ἀκοῆς αίσθητήριον ἀέρος εἶναί φαμεν.
8 And it is also reasonable that some animals have their hearing in the region around the head; for the so-called vacant space is full of air, and we say that the organ of hearing is made of air.
ἐκ μὲν σὖν τῶν ὀφύθαλμῶν οἱ πόροι φέρουσιν εἰς τἀς περὶ τὸν ἐγκέφαλον φλέβας· πάλιν δʼ ἐκ τῶν ὤτων ὡσαύτως πόρος εἰς τούπισθεν συνάπτει.
Now, the passages from the eyes lead to the veins around the brain; and again from the ears in like manner a passage connects to the back of the head.
§2.10.99 ἔχει δʼ ἐν τᾧ ἔμπροσθεν τὸν ἐγκέφαλον πάντα τὰ ἔχοντα τούτο τὸ μόριον, διὰ τὸ ἔμπροσθεν εἶναι ἑο ὅ αἰσθάνεται, τὴν δʼ αἴσθησιν ἀπὸ τῆς καρδίας, ταύτην δʼ εἶναι ἐν τσῖς ἔμπροσθεν, καὶ τὸ αίσθάνεσθαι διὰ τῶν ἐναίμων γίνεσθαι μορίων, φλεβῶν δʼ εἶναι κενὸν τὸ ὄπισθεν κύτος.
9 And all animals that have this part have the brain in the front, because that which senses is in the front, and sensation is from the heart, and this is in the front, and sensing occurs through the parts that contain blood, whereas the back cavity is devoid of veins.
τέτακται δὲ τὸν τρόπον τοῦτον τὰ αὐσθητήρια τῇ φύσει καλῶς, τὰ μὲν τῆς ἀκοῆς ἐπὶ μέσης τῆς περιφερείας (ἀκούει, γὰρ οὐ μόνον κατʼ εὐθυωρίαν ἀλλὰ πάντοθεν), ἡ δʼ ὄψις εἰς τὸ ἔμπροσθεν (ὁρᾷ γὰρ κατʼ εὐθυωρίαν, ἡ δὲ κίνησις εἰς τὸ ἔμπροσθεν, προορᾶν δὲ δεῖ ἐφʼ ὃ ἡ κίνησις).
And nature has beautifully arranged the sense organs in this way: those of hearing on the middle of the circumference (for one hears not only in a straight line but from all sides), and sight to the front (for it sees in a straight line, and movement is forward, and one must look ahead in the direction toward which the movement goes).
ἡ δὲ τῆς ὀσφρήσεως μεταξὺ τῶν ὀμμάτων εὐλόγως. διπλοῦν μὲν γάρ ἐστιν ἕκαστον τῶν αἰσθητηρίων διὰ τὸ διπλοῦν εἶναι τὸ σῶμα, τὸ μὲν δεξιὸν τὸ δʼ ἀριστερόν.
And that of smell is reasonably between the eyes; for each of the sense organs is double because the body is double, one part being the right and the other the left.
§2.10.10ἐπὶ μὲν οὖν τῆς ἁρῆς τοῦτʼ 10 ἄδηλον· τούτου δʼ αἴτιον ὅτι οὐκ ἔστι τὸ πρῶτον αἰσθητήριον ἡ σάρξ καὶ τὸ τοιοῦτον μὸριον, ἀλλʼ ἐντός.
Now, in the case of touch, this is obscure; and the cause of this is that the primary sense organ is not the flesh and suchlike part, but is inside.
ἐπὶ δὲ τῆς γλώττης ἠττον μέν, μᾶλλον δʼ ἢ ἐπὶ τῆς ἁψῆς· ἔστι γὰρ οἷον ἁρή τις καὶ αὕτη ἡ αἴσθησις.
In the case of the tongue it is less so, but more so than in the case of touch; for this sense also is a kind of touch.
ὅμως δὲ δῆλον καὶ ἐπὶ ταύτης· φαίνεται γὰρ ἐσχισμένη.
Nevertheless, it is clear also in the case of this; for it appears cleft.
ἐπὶ δὲ τῶν ἄλλων αἰσθητηρίων φανερωτέρως ἐστὶν ἡ αἴσθησις διμερής· ὦτά τε γὰρ δύο καὶ ὄμματα καὶ ἡ τῶν μυκτήρων δύναμις διφυής ἐστιν.
But in the case of the other sense organs, it is more manifest that the sense is bipartite; for there are two ears, two eyes, and the power of the nostrils is double-natured.
§2.10.11ἄλλον οὖν ἄν τρόπον κειμένη καὶ διεσπασμένη, 11 καθάπερ ἡ τῆς ἀκοῆς, οὐκ ἂν ἐποίει τὸ αὑτῆς ἔργον, οὐδὲ τὸ μόριον ἐν ᾧ ἐστίν· διὰ γὰρ τῆς ἀναπνοῆς ἡ αἴσθησις τοῖς ἔχουσι μυκτῆρας, τοῦτο δὲ τὸ μὸριον κατὰ μέσον καὶ ἐν τοῖς ἔμπροσθέν ἐστιν.
11 If, then, it were situated in another way and separated, like that of hearing, it would not perform its own function, nor would the part in which it is; for in those that have nostrils, the sensation is through respiration, and this part is in the middle and in the front.
διόπερ εἰς μέσον τῶν τριῶν αἰσθητηρίων συνήγαγεν ἡ φύσις τοὺς μυκτὴρας, οἷον ἐπὶ στάθμην θεῖσα μίαν ἐπὶ τὴν τῆς ἀνατνοῆς κίνησιν.
Therefore, nature has gathered the nostrils into the middle of the three sense organs, placing them as if on a single plumb-line for the movement of respiration.
καλῶς δὲ καὶ τοῖς ἄλλοις ἔχει ταῦτα τὰ αἰσθητήρια ζῴοις πρὸς τὴν ἰδίαν φύσιν ἑκάστῳ.
And these sense organs are beautifully situated also for the other animals in relation to each of their own natures.