ΠΕΡΙ ΥΠΝΟΥ ΚΑΙ ΕΓΡΗΓΟΡΣΕΩΣ
453 b I. Περὶ δὲ ὕπνου καὶ ἐγρηγόρσεως σκεπτέον, τίνα τε τυγχάνει ὄντα, καὶ πότερον ἴδια τῆς ψυχῆς ἢ τοῦ σώματος ἢ κοινά, κἂν ᾖ κοινά, τίνος μορίου τῆς ψυχῆς ἢ τοῦ σώματος· καὶ διὰ τίν᾿ αἰτίαν ὑπάρχει 15τοῖς ζῴοις· καὶ πότερον ἅπαντα κεκοινώνηκεν αὐτῶν ἀμφοτέρων, ἢ τὰ μὲν ὕπνου τὰ δὲ θατέρου μόνον, ἢ τὰ μὲν οὐδετέρου τὰ δ᾿ ἀμφοτέρων· πρὸς δὲ τούτοις τί ἐστι τὸ ἐνύπνιον, καὶ διὰ τίν᾿ αἰτίαν οἱ καθεύδοντες ὁτὲ μὲν ὀνειρώττουσιν ὁτὲ δ᾿ οὔ· ἢ συμβαίνει μὲν ἀεὶ τοῖς καθεύδουσιν ἐνυπνιάζειν, 20ἀλλ᾿ οὐ μνημονεύουσιν· καὶ εἰ τοῦτο γίνεται, διὰ τίνα αἰτίαν γίνεται· καὶ πότερον ἐνδέχεται τὰ μέλλοντα προορᾶν ἢ οὐκ ἐνδέχεται, καὶ τίνα τρόπον, εἰ ἐνδέχεται· καὶ πότερον τὰ μέλλοντα ὑπ᾿ ἀνθρώπου πράσσεσθαι μόνον, ἢ καὶ ὧν τὸ δαιμόνιον ἔχει τὴν αἰτίαν καὶ φύσει γίνεται ἢ ἀπὸ ταὐτομάτου.
25Πρῶτον μὲν οὖν τοῦτό γε φανερόν, ὅτι τῷ αὐτῷ τοῦ ζῴου ἥ τε ἐγρήγορσις ὑπάρχει καὶ ὁ ὕπνος· ἀντίκεινται γάρ, καὶ φαίνεται στέρησίς τις ὁ ὕπνος τῆς ἐγρηγόρσεως· ἀεὶ γὰρ τὰ ἐναντία καὶ ἐπὶ τῶν ἄλλων καὶ ἐν τοῖς φυσικοῖς ἐν τῷ αὐτῷ δεκτικῷ
On Sleep and Waking
I. We have now to turn our attention to sleep andProblems arising from the subject. waking. What are they? Are they peculiar to the soul or to the body, or do they belong to both? If they belong to both, to what part of the soul or body do they belong? Why are they characteristic of animals? Do all animals share in both, or do some share in sleep only, and others in waking only, or some in neither and others in both? Furthermore what is a dream, and why do men when asleep sometimes dream and sometimes not? Or do sleepers always dream, but sometimes fail to remember their dreams? If the latter is true, why does it occur? Is it possible or impossible to foresee the future? If it is possible, in what way? Again, does the possibility cover only actions to be performed by man, or those also which are due to superhuman agency and are brought about naturally or spontaneously?
To begin with, this at any rate is obvious, thatsleep and wakefulness are complementary. waking and sleep belong to the same part of the animal; for they are opposites, and sleep is apparently a privation of waking; for in natural objects, as in all other cases, contraries evidently occur in the same receptive material, and are affections of the