For this cause too it seems to me that it has been granted a more secure defence, being distinguished, in the head, by a double shelter of bones round about, and in the vertebrae of the neck by the bulwarks formed by the projections of the spine as well as by the diversified interlacings of the very form of those vertebrae, by which it is kept in freedom from all harm, enjoying safety by the defence that surrounds it. So too one might suppose of the heart, that it is itself like some safe house fitted with the most solid defences, fortified by the enclosing walls of the bones round about; for in rear there is the spine, strengthened on either side by the shoulder-blades, and on each flank the enfolding position of the ribs makes that which is in the midst between them difficult to injure; while in front the breast-bone and the juncture of the collar-bone serve as a defence, that its safety may be guarded at all points from external causes of danger. As we see in husbandry, when the rain fall from the clouds or the overflow from the river channels causes the land beneath it to be saturated with moisture (let us suppose for our argument a garden, nourishing within its own compass countless varieties of trees, and all the forms of plants that grow from the ground, and whereof we contemplate the figure, quality, and individuality in great variety of detail); then, as these are nourished by the liquid element while they are in one spot, the power which supplies moisture to each individual among them is one in nature; but the individuality of the plants so nourished changes the liquid element into different qualities; for the same substance becomes bitter in wormwood, and is changed into a deadly juice in hemlock, and becomes different in different other plants, in saffron, in balsam, in the poppy: for in one it becomes hot, in another cold, in another it obtains the middle quality: and in laurel and mastick it is scented, and in the fig and the pear it is sweetened, and by passing through the vine it is turned into the grape and into wine; while the juice of the apple, the redness of the rose, the radiance of the lily, the blue of the violet, the purple of the hyacinthine dye, and all that we behold in the earth, arise from one and the same moisture, and are separated into so many varieties in respect of figure and aspect and quality; the same sort of wonder is wrought in the animated soil of our being by Nature, or rather by Nature's Lord. Bones, cartilages, veins, arteries, nerves, ligatures, flesh, skin, fat, hair, glands, nails, eyes, nostrils, ears,-all such things as these, and countless others in addition, while separated from one another by various peculiarities, are nourished by the one form of nourishment in ways proper to their own nature, in the sense that the nourishment, when it is brought into close relation with any of the subjects, is also changed according to that to which it approaches, and becomes adapted and allied to the special nature of the part. For if it should be in the neighbourhood of the eye, it blends with the visual part and is appropriately distributed by the difference of the coats round the eye, among the single parts; or, if it flow to the auditory parts, it is mingled with the auscultatory nature, or if it is in the lip, it becomes lip; and it grows solid in bone, and grows soft in marrow, and is made tense with the sinew, and extended with the surface, and passes into the nails, and is fined down for the growth of the hair, by correspondent exhalations, producing hair that is somewhat curly or wavy if it makes its way through winding passages, while, if the course of the exhalations that go to form the hair lies straight, it renders the hair stiff and straight.

[252] Διὰ τοῦτό μοι δοκεῖ καὶ ἀσφαλεστέρας ἠξιῶσθαι φρουρᾶς καὶ κατὰ μὲν τὴν κεφαλὴν διπλαῖς ὀστέων περιβολαῖς ἐν κύκλῳ διειλημμένος͵ ἐν δὲ τοῖς σπονδύλοις ταῖς τε τῶν ἀκανθῶν προβολαῖς καὶ ταῖς πολυτρόποις κατὰ τὸ σχῆμα διαπλοκαῖς͵ δι' ὧν ἐν ἀπαθείᾳ πάσῃ φυλάττεται͵ διὰ τῆς περιεχούσης αὐτὸν φρουρᾶς τὸ ἀσφαλὲς ἔχων. Ὁμοίως δ' ἄν τις καὶ περὶ τῆς καρδίας στοχάσαιτο͵ ὅτι καθάπερ τις οἶκος ἀσφαλὴς αὕτη διὰ τῶν στεῤῥοτάτων περιηρμόσθη ταῖς τῶν ὀστέων ἐν κύκλῳ περιοχαῖς ὠχυρωμένη. Κατόπιν μὲν γάρ ἐστιν ἡ ῥάχις ταῖς ὠμοπλάταις ἑκατέρωθεν ἠσφαλισμένη. Καθ' ἑκάτερον δὲ πλάγιον ἡ τῶν πλευρῶν θέσις περιπτύσσουσα τὸ μέσον δυσπαθὲς ἀπεργάζεται. Ἐν δὲ τοῖς ἔμπροσθεν τὸ στέρνον καὶ ἡ τῆς κλειδὸς συζυγία προβέβληται͵ ὡς ἂν πανταχόθεν αὐτῇ τὸ ἀσφαλὲς ἀπὸ τῶν ἔξωθεν διοχλούντων φυλάσσοιτο. Οἷον δὲ κατὰ τὴν γεωργίαν ἔστιν ἰδεῖν͵ τῆς ἐκ νεφῶν ἐπομβρίας ἢ τῆς τῶν ὀχετῶν ἐπιῤῥοῆς διάβροχον ποιούσης τὸ ὑποκείμενον. Κῆπος δέ τις ὑποκείσθω τῷ λόγῳ͵ μυρίας μὲν δένδρων διαφοράς͵ παντοδαπὰς δὲ τῶν ἐκ γῆς φυομένων ἰδέας ἐν ἑαυτῷ τρέφων͵ ὧν καὶ τὸ σχῆμα καὶ ἡ ποιότης καὶ ἡ τῆς χρόας ἰδιότης ἐν πολλῇ διαφορᾷ τοῖς καθέκαστον ἐνθεωρεῖται. Τοσούτων τοίνυν κατὰ τὸν ἕνα χῶρον τῷ ὑγρῷ τρεφομένων͵ ἡ μὲν ὑπονοτίζουσα τὰ καθ' ἕκαστον δύναμις μία τις κατὰ τὴν φύσιν ἐστίν, ἡ δὲ τῶν τρεφομένων ἰδιότης εἰς διαφόρους τὸ ὑγρὸν μεταβάλλει ποιότητας. Τὸ γὰρ αὐτὸ πικραίνεται μὲν ἐν τῇ ἀψίνθῳ, εἰς φθοροποιὸν δὲ χυμὸν ἐν τῷ κωνείῳ μεθίσταται, καὶ ἄλλο ἐν ἄλλῳ γίνεται͵ ἐν κρόκῳ͵ ἐν βαλσάμῳ͵ ἐν μήκωνι. Τῷ μὲν γὰρ ἐκθερμαίνεται͵ τῷ δὲ καταψύχεται͵ τῷ δὲ μέσην ἔχει ποιότητα. Καὶ ἐν δάφνῃ καὶ ἐν σχοίνῳ καὶ τοῖς τοιούτοις εὔπνουν ἐστίν, ἐν συκῇ δὲ καὶ ὄχνῃ κατεγλυκάνθη. Καὶ διὰ τῆς ἀμπέλου βότρυς καὶ οἶνος ἐγένετο, καὶ ὁ τοῦ μήλου χυλὸς καὶ τὸ τοῦ ῥόδου ἐρύθρημα καὶ τὸ τοῦ κρίνου λαμπρὸν καὶ τὸ κυανίζον τοῦ ἴου καὶ τὸ πορφυραῖον τῆς ὑακίνθου βαφῆς καὶ πάνθ' ὅσα κατὰ τὴν γῆν ἔστιν ἰδεῖν͵ ἐκ μιᾶς καὶ τῆς αὐτῆς ἰκμάδος ἀναβλαστάνοντα͵ εἰς τοσαύτας διαφορὰς κατά τε τὸ σχῆμα καὶ τὸ εἶδος καὶ τὰς ποιότητας διακρίνεται. Τοιοῦτόν τι καὶ κατὰ τὴν ἔμψυχον ἡμῶν ἄρουραν θαυματοποιεῖται παρὰ τῆς φύσεως͵ μᾶλλον δὲ παρὰ τοῦ Δεσπότου φύσεως. Ὀστέα καὶ χόνδροι͵ φλέβες͵ ἀρτηρίαι͵ νεῦρα͵ σύνδεσμοι͵ σάρκες͵ δέρμα͵ πιμελαί͵ τρίχες͵ ἀδένες͵ ὄνυχες͵ ὀφθαλμοί͵ μυκτῆρες͵ ὦτα͵ πάντα τὰ τοιαῦτα καὶ μυρία πρὸς τούτοις ἄλλα διαφόροις ἰδιότησιν ἀπ' ἀλλήλων κεχωρισμένα͵ μιᾷ τῇ τῆς τροφῆς ἰδέᾳ καταλλήλως τῇ ἑαυτῶν τρέφεται φύσει͵ ὡς ἑκάστῳ τῶν ὑποκειμένων τὴν τροφὴν προσεγγίσασαν͵ ᾧπερ ἂν ἐμπελάσῃ͵ κατ' ἐκεῖνο καὶ ἀλλοιοῦσθαι͵ οἰκείαν καὶ συμφυῆ τῇ τοῦ μέρους ἰδιότητι γινομένην. Εἰ γὰρ κατὰ τὸν ὀφθαλμὸν γένοιτο͵ τῷ ὁρατικῷ μορίῳ συγκατεκράθη͵ [253] καὶ τῶν περὶ τὸν ὀφθαλμὸν χιτώνων ταῖς διαφοραῖς οἰκείως εἰς ἕκαστον κατεμερίσθη, εἰ δὲ τοῖς κατὰ τὴν ἀκοὴν μέρεσιν ἐπιῤῥυῇ͵ τῇ ἀκουστικῇ καταμίγνυται φύσει, καὶ ἐν χείλει γενόμενον͵ χεῖλος ἐγένετο, καὶ ἐν ὀστέῳ πήγνυται καὶ ἐν μυελῷ ἁπαλύνεται καὶ τονοῦται μετὰ τοῦ νεύρου καὶ τῇ ἐπιφανείᾳ συμπεριτείνεται καὶ εἰς ὄνυχας διαβαίνει καὶ εἰς τριχῶν γένεσιν λεπτοποιεῖται τοῖς καταλλήλοις ἀτμοῖς. Εἰ μὲν διὰ σκολιῶν προάγοιτο πόρων͵ οὐλοτέρας τε καὶ κατηγκυλωμένας τὰς τρίχας ἐκφύουσα͵ εἰ δὲ δι' εὐθείας ἡ τῶν τριχοποιῶν ἀτμῶν γένοιτο πρόοδος͵ τεταμένας τε καὶ εὐθείας προάγουσα.