LCL 288: 396-397
465 a γένη, καὶ τῶν ὑφ᾿ ἓν εἶδος ἕτερα πρὸς ἕτερα. λέγω 5δὲ κατὰ γένος μὲν διαφέρειν οἷον ἄνθρωπον πρὸς ἵππον (μακροβιώτερον γὰρ τὸ τῶν ἀνθρώπων γένος ἢ τὸ τῶν ἵππων), κατ᾿ εἶδος δ᾿ ἄνθρωπον πρὸς ἄνθρωπον· εἰσὶ γὰρ καὶ ἄνθρωποι οἱ μὲν μακρόβιοι οἱ δὲ βραχύβιοι ἕτεροι καθ᾿ ἑτέρους τόπους διεστῶτες· τὰ μὲν γὰρ ἐν τοῖς θερμοῖς τῶν ἐθνῶν μακροβιώτερα, 10τὰ δ᾿ ἐν τοῖς ψυχροῖς βραχυβιώτερα. καὶ τῶν τὸν αὐτὸν δὲ τόπον οἰκούντων διαφέρουσιν ὁμοίως τινὲς ταύτην πρὸς ἀλλήλους τὴν διαφοράν.
II. Δεῖ δὴ λαβεῖν τί τὸ εὔφθαρτον ἐν τοῖς φύσει συνεστῶσι καὶ τί τὸ οὐκ εὔφθαρτον. πῦρ γὰρ καὶ 15ὕδωρ καὶ τὰ τούτοις συγγενῆ, οὐκ ἔχοντα τὴν αὐτὴν δύναμιν, τυγχάνει γενέσεως καὶ φθορᾶς αἴτια ἀλλήλοις, ὥστε καὶ τῶν ἄλλων ἕκαστον ἐκ τούτων ὄντα καὶ συνεστῶτα μετέχειν τῆς τούτων φύσεως εὔλογον, ὅσα μὴ συνθέσει ἐκ πολλῶν ἐστίν, οἷον οἰκία. περὶ μὲν οὖν τῶν ἄλλων ἕτερος λόγος· 20εἰσὶ γὰρ ἴδιαι φθοραὶ πολλοῖς τῶν ὄντων, οἷον ἐπιστήμῃ καὶ ὑγιείᾳ καὶ νόσῳ· ταῦτα γὰρ φθείρεται καὶ μὴ φθειρομένων τῶν δεκτικῶν ἀλλὰ σωζομένων·, οἷον ἀγνοίας μὲν φθορὰ ἀνάμνησις καὶ μάθησις, ἐπιστήμης δὲ λήθη καὶ ἀπάτη. κατὰ συμβεβηκὸς 25δ᾿ ἀκολουθοῦσι τοῖς φυσικοῖς αἱ τῶν ἄλλων φθοραί· φθειρομένων γὰρ τῶν ζῴων φθείρεται καὶ ἡ ἐπιστήμη καὶ ἡ ὑγίεια ἡ ἐν τοῖς ζῴοις.
Διὸ καὶ περὶ ψυχῆς συλλογίσαιτ᾿ ἄν τις ἐκ τούτων· εἰ γάρ ἐστι μὴ φύσει ἀλλ᾿ ὥσπερ ἐπιστήμη ἐν ψυχῇ, οὕτω καὶ ψυχὴ ἐν σώματι, εἴη ἄν τις αὐτῆς
wholes, but also between groups of individuals included under one species. By differences in genus I mean e.g. that between man and horse (for the genus man is longer-lived than the genus horse), and by difference within a species that between man and man; for of men too some are long-lived, and some short-lived, differing according to their different localities; for races living in hot countries live longer than those in cold countries. Some even of those who live in the same locality exhibit similar differences from one another.
II. We must of course grasp what it is amongThe sources of destruction. natural objects that makes them easily destroyed or the reverse. For fire, water, and the kindred elements, not all having the same power, are reciprocal causes of each other’s generation and destruction, so that it is only natural that anything proceeding from or consisting of these elements should share in their nature, except for things formed by a combination of numerous parts, such as a house. With regard to all other things it is a different story; for many things, such as knowledge, health, and disease, have their own peculiar forms of destruction. They can be destroyed even when what contains them is not destroyed, but continues to exist: for instance, learning and recollection destroy ignorance, and forgetfulness and error destroy knowledge. But in an accidental sense the destruction of these other things follows the destruction of natural objects, for when living creatures are destroyed, the knowledge or health that is in them is destroyed also.
From these facts one might come to some conclusionSoul and body. about the soul, for if the soul is not by its own nature contained in a body, but only in the way in which knowledge is contained in the soul, it might be