Chapter VI.—Everything that is Useless or Hurtful is Rejected.

Since, therefore, great difference of nature obtains in all animals, and the very nourishment which is accordant with nature is varied to suit each kind of animal, and the body which is nourished; and as in the nourishment of every animal there is a threefold cleansing and separation, it follows that whatever is alien from the nourishment of the animal must be wholly destroyed and carried off to its natural place, or change into something else, since it cannot coalesce with it; that the power of the nourishing body must be suitable to the nature of the animal to be nourished, and accordant with its powers; and that this, when it has passed through the strainers appointed for the purpose, and been thoroughly purified by the natural means of purification, must become a most genuine addition to the substance,—the only thing, in fact, which any one calling things by their right names would call nourishment at all; because it rejects everything that is foreign and hurtful to the constitution of the animal nourished and that mass of superfluous food introduced merely for filling the stomach and gratifying the appetite. This nourishment, no one can doubt, becomes incorporated with the body that is nourished, interwoven and blended with all the members and parts of members; but that which is different and contrary to nature is speedily corrupted if brought into contact with a stronger power, but easily destroys that which is overcome by it, and is converted into hurtful humours and poisonous qualities, because producing nothing akin or friendly to the body which is to be nourished. And it is a very clear proof of this, that in many of the animals nourished, pain, or disease, or death follows from these things, if, owing to a too keen appetite, they take in mingled with their food something poisonous and contrary to nature; which, of course, would tend to the utter destruction of the body to be nourished, since that which is nourished is nourished by substances akin to it and which accord with its nature, but is destroyed by those of a contrary kind. If, therefore, according to the different nature of animals, different kinds of food have been provided suitable to their nature, and none of that which the animal may have taken, not even an accidental part of it, admits of being blended with the body which is nourished, but only that part which has been purified by an entire digestion, and undergone a complete change for union with a particular body, and adapted to the parts which are to receive nourishment,—it is very plain that none of the things contrary to nature can be united with those bodies for which it is not a suitable and correspondent nourishment, but either passes off by the bowels before it produces some other humour, crude and corrupted; or, if it continue for a longer time, produces suffering or disease hard to cure, destroying at the same time the natural nourishment, or even the flesh itself which needs nourishment. But even though it be expelled at length, overcome by certain medicines, or by better food, or by the natural forces, it is not got rid of without doing much harm, since it bears no peaceful aspect towards what is natural, because it cannot coalesce with nature.

Πολλῆς οὖν οὔσης ἐν πᾶσι τοῖς ζῴοις τῆς φυσικῆς διαφορᾶς καὶ αὐτῆς γε τῆς κατὰ φύσιν τροφῆς ἑκάστῳ γένει ζῴων καὶ τῷ τρεφομένῳ σώματι συνεξαλλαττομένης, τριττῆς δὲ κατὰ τὴν ἑκάστου ζῴου τροφὴν γινομένης καθάρσεως καὶ διακρίσεως, δεῖ πάντως φθείρεσθαι μὲν καὶ διαχωρεῖν ᾗ πέφυκεν ἢ πρὸς ἕτερόν τι μεταβάλλειν πᾶν ὁπόσον ἀλλότριον εἰς τὴν τοῦ ζῴου τροφὴν ὡς συγκραθῆναι μὴ δυνάμενον, συμβαίνουσαν δὲ καὶ κατὰ φύσιν εἶναι τὴν τοῦ τρέφοντος σώματος δύναμιν ταῖς τοῦ τρεφομένου ζῴου δυνάμεσιν καὶ ταύτην ἐλθοῦσαν δι' ὧν πέφυκεν κριτηρίων καὶ καθαρθεῖσαν ἀκριβῶς τοῖς φυσικοῖς καθαρσίοις εἰλικρινεστάτην γενέσθαι πρόσληψιν εἰς οὐσίαν· ἣν δὴ καὶ μόνην ἐπαληθεύων ἄν τις τοῖς πράγμασιν ὀνομάσειεν τροφὴν ὡς ἀποβάλλουσαν πᾶν ὁπόσον ἀλλότριον καὶ βλαβερὸν εἰς τὴν τοῦ τρεφομένου ζῴου σύστασιν καὶ τὸν πολὺν ἐκεῖνον ὄγκον ἐπεισαχθέντα πρὸς τὴν τῆς γαστρὸς ἀποπλήρωσιν καὶ τὴν τῆς ὀρέξεως θεραπείαν. ἀλλὰ ταύτην μὲν οὐκ ἄν τις ἀμφισβητήσειεν ἑνοῦσθαι τῷ τρεφομένῳ σώματι συνδιαπλεκομένην τε καὶ περιπλαττομένην πᾶσι τοῖς τούτου μέρεσιν καὶ μορίοις· τὴν δ' ἑτέρως ἔχουσαν καὶ παρὰ φύσιν φθείρεσθαι μὲν ταχέως, ἢν ἐρρωμενεστέρᾳ συμμίξῃ δυνάμει, φθείρειν δὲ σὺν εὐμαρείᾳ τὴν κρατηθεῖσαν εἴς τε μοχθηροὺς ἐκτρέπεσθαι χυμοὺς καὶ φαρμακώδεις ποιότητας ὡς μηδὲν οἰκεῖον ἢ φίλον τῷ τρεφομένῳ σώματι φέρουσαν. καὶ τούτου τεκμήριον μέγιστον τὸ πολλοῖς τῶν τρεφομένων ζῴων ἐκ τούτων ἐπακολουθεῖν ἄλγος ἢ κίνδυνον ἢ θάνατον, ἢν ὑπὸ σφοδροτέρας ὀρέξεως τῇ τροφῇ καταμεμιγμένον συνεφελκύσηταί τι φαρμακῶδες καὶ παρὰ φύσιν· ὃ δὴ καὶ πάντως φθαρτικὸν ἂν εἴη τοῦ τρεφομένου σώματος, εἴ γε τρέφεται μὲν τὰ τρεφόμενα τοῖς οἰκείοις καὶ κατὰ φύσιν, φθείρεται δὲ τοῖς ἐναντίοις. εἴπερ οὖν τῇ διαφορᾷ τῶν τῇ φύσει διαφερόντων ζῴων ἡ κατὰ φύσιν συνδιῄρηται τροφὴ καὶ ταύτης γε αὐτῆς οὔτε πᾶν ὅπερ ἂν προσενέγκηται τὸ ζῷον οὔτε τὸ τυχὸν ἐκ τούτου τὴν πρὸς τὸ τρεφόμενον σῶμα δέχεται σύγκρασιν, ἀλλ' αὐτὸ μόνον τὸ διὰ πάσης πέψεως κεκαθαρμένον καὶ μεταβεβληκὸς εἰλικρινῶς πρὸς τὴν τοῦ ποιοῦ σώματος ἕνωσιν καὶ τοῖς τρεφομένοις μέρεσιν εὐάρμοστον, εὔδηλον ὡς οὐδὲν τῶν παρὰ φύσιν ἑνωθείη ποτ' ἂν τούτοις οἷς οὔκ ἐστιν τροφὴ προσφυὴς καὶ κατάλληλος, ἀλλ' ἤτοι κατ' αὐτὴν τὴν κοιλίαν διαχωρεῖ πρὶν ἕτερόν τινα γεννῆσαι χυμὸν ὠμὸν καὶ διεφθαρμένον, ἢ συστὰν ἐπὶ πλεῖον τίκτει πάθος ἢ νόσον δυσίατον, συνδιαφθείρουσαν καὶ τὴν κατὰ φύσιν τροφὴν ἢ καὶ αὐτὴν τὴν τῆς τροφῆς δεομένην σάρκα. ἀλλὰ κἂν ἀπωσθῇ ποτε φαρμάκοις τισὶν ἢ σιτίοις βελτίοσιν ἢ ταῖς φυσικαῖς δυνάμεσι νικηθέν, μετ' οὐκ ὀλίγης ἐξερρύη τῆς βλάβης ὡς μηδὲν φέρον τοῖς κατὰ φύσιν εἰρηνικὸν διὰ τὸ πρὸς τὴν φύσιν ἀσύγκρατον.