Bone was composed by him in the following manner. Having sifted pure and smooth earth he kneaded it and wetted it with marrow, and after that he put it into fire and then into water, and once more into fire and again into water-in this way by frequent transfers from one to the other he made it insoluble by either. Out of this he fashioned, as in a lathe, a globe made of bone, which he placed around the brain, and in this he left a narrow opening; and around the marrow of the neck and back he formed vertebrae which he placed under one another like pivots, beginning at the head and extending through the whole of the trunk. Thus wishing to preserve the entire seed, he enclosed it in a stone-like casing, inserting joints, and using in the formation of them the power of the other or diverse as an intermediate nature, that they might have motion and flexure. Then again, considering that the bone would be too brittle and inflexible, and when heated and again cooled would soon mortify and destroy the seed within-having this in view, he contrived the sinews and the flesh, that so binding all the members together by the sinews, which admitted of being stretched and relaxed about the vertebrae, he might thus make the body capable of flexion and extension, while the flesh would serve as a protection against the summer heat and against the winter cold, and also against falls, softly and easily yielding to external bodies, like articles made of felt; and containing in itself a warm moisture which in summer exudes and makes the surface damp, would impart a nature coolness to the whole body; and again in winter by the help of this internal warmth would form a very tolerable defence against the frost which surrounds it and attacks it from without.

[73e] τὸ δὲ ὀστοῦν συνίστησιν ὧδε. γῆν διαττήσας καθαρὰν καὶ λείαν ἐφύρασε καὶ ἔδευσεν μυελῷ͵ καὶ μετὰ τοῦτο εἰς πῦρ αὐτὸ ἐντίθησιν͵ μετ΄ ἐκεῖνο δὲ εἰς ὕδωρ βάπτει͵ πάλιν δὲ εἰς πῦρ͵ αὖθίς τε εἰς ὕδωρ· μεταφέρων δ΄ οὕτω πολλάκις εἰς ἑκάτερον ὑπ΄ ἀμφοῖν ἄτηκτον ἀπηργάσατο. καταχρώμενος δὴ τούτῳ περὶ μὲν τὸν ἐγκέφαλον αὐτοῦ σφαῖραν περιετόρνευσεν ὀστεΐνην͵ ταύτῃ δὲ στενὴν διέξοδον κατελείπετο· [74a] καὶ περὶ τὸν διαυχένιον ἅμα καὶ νωτιαῖον μυελὸν ἐξ αὐτοῦ σφονδύλους πλάσας ὑπέτεινεν οἷον στρόφιγγας͵ ἀρξάμενος ἀπὸ τῆς κεφαλῆς͵ διὰ παντὸς τοῦ κύτους. καὶ τὸ πᾶν δὴ σπέρμα διασῴζων οὕτως λιθοειδεῖ περιβόλῳ συνέφραξεν͵ ἐμποιῶν ἄρθρα͵ τῇ θατέρου προσχρώμενος ἐν αὐτοῖς ὡς μέσῃ ἐνισταμένῃ δυνάμει͵ κινήσεως καὶ κάμψεως ἕνεκα. [74b] τὴν δ΄ αὖ τῆς ὀστεΐνης φύσεως ἕξιν ἡγησάμενος τοῦ δέοντος κραυροτέραν εἶναι καὶ ἀκαμπτοτέραν͵ διάπυρόν τ΄ αὖ γιγνομένην καὶ πάλιν ψυχομένην σφακελίσασαν ταχὺ διαφθερεῖν τὸ σπέρμα ἐντὸς αὑτῆς͵ διὰ ταῦτα οὕτω τὸ τῶν νεύρων καὶ τὸ τῆς σαρκὸς γένος ἐμηχανᾶτο͵ ἵνα τῷ μὲν πάντα τὰ μέλη συνδήσας ἐπιτεινομένῳ καὶ ἀνιεμένῳ περὶ τοὺς στρόφιγγας καμπτόμενον τὸ σῶμα καὶ ἐκτεινόμενον παρέχοι͵ τὴν δὲ σάρκα προβολὴν μὲν καυμάτων͵ πρόβλημα δὲ χειμώνων͵ ἔτι δὲ πτωμάτων οἷον τὰ πιλητὰ ἔσεσθαι κτήματα͵ [74c] σώμασιν μαλακῶς καὶ πρᾴως ὑπείκουσαν͵ θερμὴν δὲ νοτίδα ἐντὸς ἑαυτῆς ἔχουσαν θέρους μὲν ἀνιδίουσαν καὶ νοτιζομένην ἔξωθεν ψῦχος κατὰ πᾶν τὸ σῶμα παρέξειν οἰκεῖον͵ διὰ χειμῶνος δὲ πάλιν αὖ τούτῳ τῷ πυρὶ τὸν προσφερόμενον ἔξωθεν καὶ περιιστάμενον πάγον ἀμυνεῖσθαι μετρίως.