Ross (OCT, 1955) · Beare (1908)
Beare (1908)
Chapter 1 (453b11–455a3)
453b
Περὶ δὲ ὕπνου καὶ ἐγρηγόρσεως ἐπισκεπτέον
τίνα τε τυγχάνει ὄντα, καὶ πότερον ἴδια τῆς ψυχῆς ἢ τοῦ
σώματος ἢ κοινά, καὶ εἰ κοινά, τίνος μορίου τῆς ψυχῆς ἢ
τοῦ σώματος, καὶ διὰ τίν' αἰτίαν ὑπάρχει τοῖς ζῴοις· καὶ
15 πότερον ἅπαντα κεκοινώνηκεν ἀμφοτέρων, ἢ τὰ μὲν
θατέρου τὰ δὲ θατέρου μόνον, ἢ τὰ μὲν οὐδετέρου τὰ δὲ ἀμφοτέρων·
πρὸς δὲ τούτοις τί ἐστι τὸ ἐνύπνιον, καὶ διὰ τίνα αἰτίαν
οἱ καθεύδοντες ὁτὲ μὲν ὀνειρώττουσιν ὁτὲ δὲ οὔ, ἢ συμβαίνει
μὲν ἀεὶ τοῖς καθεύδουσιν ἐνυπνιάζειν, ἀλλ' οὐ μνημονεύουσιν,
20 καὶ εἰ τοῦτο γίγνεται, διὰ τίνα αἰτίαν γίγνεται· 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 γίγνεται ἢ ἀπὸ ταὐτομάτου. πρῶτον μὲν οὖν
25 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 φαίνεται
γιγνόμενα, καὶ τοῦ αὐτοῦ ὄντα πάθη, λέγω δ' οἷον ὑγίεια καὶ
30 νόσος, καὶ κάλλος καὶ αἶσχος, καὶ ἰσχὺς καὶ ἀσθένεια,
καὶ ὄψις καὶ τυφλότης, καὶ ἀκοὴ καὶ κωφότης. ἔτι δὲ
11With regard to sleep and waking, we must consider what they are: whether they are peculiar to soul or to body, or common to both; and if common, to what part of soul or body they appertain: further, from what cause it arises that they are attributes of animals, and 15whether all animals share in them both, or some partake of the one only, others of the other only, or some partake of neither and some of both.
Further, in addition to these questions, we must also inquire what the dream is, and from what cause sleepers sometimes dream, and sometimes do not; or whether the truth is that sleepers always dream but do not always remember (their dream); 20and if this occurs, what its explanation is.
Again, [we must inquire] whether it is possible or not to foresee the future (in dreams), and if it be possible, in what manner; further, whether, supposing it possible, it extends only to things to be accomplished by the agency of Man, or to those also of which the cause lies in supra-human agency, and which result from the workings of Nature, or of Spontaneity.
First, then, 25this much is clear, that waking and sleep appertain to the same part of an animal, inasmuch as they are opposites, and sleep is evidently a privation of waking. For contraries, in natural as well as in all other matters, are seen always to present themselves in the same subject, and to be affections of the same: examples are-health and sickness, 30beauty and ugliness, strength and weakness, sight and blindness, hearing and deafness. This is also clear from the following considerations. The criterion by which we know the waking person to be awake is identical with that by which we know the sleeper to be asleep; for we assume that one who is exercising sense-perception is awake, and that every one who is awake perceives either some external movement or else some movement in his own consciousness.
Further, in addition to these questions, we must also inquire what the dream is, and from what cause sleepers sometimes dream, and sometimes do not; or whether the truth is that sleepers always dream but do not always remember (their dream); 20and if this occurs, what its explanation is.
Again, [we must inquire] whether it is possible or not to foresee the future (in dreams), and if it be possible, in what manner; further, whether, supposing it possible, it extends only to things to be accomplished by the agency of Man, or to those also of which the cause lies in supra-human agency, and which result from the workings of Nature, or of Spontaneity.
First, then, 25this much is clear, that waking and sleep appertain to the same part of an animal, inasmuch as they are opposites, and sleep is evidently a privation of waking. For contraries, in natural as well as in all other matters, are seen always to present themselves in the same subject, and to be affections of the same: examples are-health and sickness, 30beauty and ugliness, strength and weakness, sight and blindness, hearing and deafness. This is also clear from the following considerations. The criterion by which we know the waking person to be awake is identical with that by which we know the sleeper to be asleep; for we assume that one who is exercising sense-perception is awake, and that every one who is awake perceives either some external movement or else some movement in his own consciousness.
454a
1 καὶ ἐκ τῶνδε δῆλον· ᾧ γὰρ τὸν ἐγρηγορότα γνωρίζομεν,
τούτῳ καὶ τὸν καθυπνοῦντα· τὸν δὲ αἰσθανόμενον ἐγρηγορέναι
νομίζομεν, καὶ τὸν ἐγρηγορότα πάντα ἢ τῶν ἔξωθέν τινος αἰσθάνεσθαι
ἢ τῶν ἐν αὑτῷ κινήσεων. εἰ τοίνυν τὸ ἐγρηγορέναι
5 ἐν μηδενὶ ἄλλῳ ἐστὶν ἢ τῷ αἰσθάνεσθαι, δῆλον ὅτι ᾧ περ αἰσθάνεται,
τούτῳ καὶ ἐγρήγορε τὰ ἐγρηγορότα καὶ καθεύδει
τὰ καθεύδοντα. ἐπεὶ δὲ οὔτε τῆς ψυχῆς ἴδιον τὸ αἰσθάνεσθαι
οὔτε τοῦ σώματος (οὗ γὰρ ἡ δύναμις, τούτου καὶ ἡ ἐνέργεια· ἡ
δὲ λεγομένη αἴσθησις ὡς ἐνέργεια κίνησίς τις διὰ τοῦ σώματος
10 τῆς ψυχῆς ἐστι), φανερὸν ὡς οὔτε τῆς ψυχῆς τὸ πάθος
ἴδιον, οὔτ' ἄψυχον σῶμα δυνατὸν αἰσθάνεσθαι. διωρισμένων
δὲ πρότερον ἐν ἑτέροις περὶ τῶν λεγομένων ὡς μορίων
τῆς ψυχῆς, καὶ τοῦ μὲν θρεπτικοῦ χωριζομένου τῶν ἄλλων ἐν
τοῖς ἔχουσι σώμασι ζωήν, τῶν δ' ἄλλων οὐδενὸς ἄνευ τούτου,
15 δῆλον ὡς ὅσα μὲν αὐξήσεως καὶ φθίσεως μετέχει μόνον
τῶν ζώντων, [ὅτι] τούτοις οὐχ ὑπάρχει ὕπνος οὐδὲ ἐγρήγορσις,
οἷον τοῖς φυτοῖς (οὐ γὰρ ἔχουσι τὸ αἰσθητικὸν μόριον, οὔτε εἰ
χωριστόν ἐστιν οὔτε εἰ μὴ χωριστόν· τῇ γὰρ δυνάμει καὶ τῷ
εἶναι χωριστόν ἐστιν)· ὁμοίως δὲ καὶ ὅτι οὐδέν ἐστιν ὃ ἀεὶ ἐγρήγορεν
20 ἢ ἀεὶ καθεύδει, ἀλλὰ τοῖς αὐτοῖς ὑπάρχει τῶν ζῴων
ἀμφότερα τὰ πάθη ταῦτα. οὐ γάρ, εἴ τι ἔστι ζῷον <μὴ> ἔχον
αἴσθησιν, τοῦτ' ἐνδέχεται οὔτε καθεύδειν οὔτε ἐγρηγορέναι (ἄμφω
γάρ ἐστι τὰ πάθη ταῦτα περὶ αἴσθησιν τοῦ πρώτου αἰσθητικοῦ)·
οὐκ ἐνδέχεται δὲ οὐδὲ θάτερον τούτων ἀεὶ ὑπάρχειν
25 τῷ αὐτῷ, οἷον ἀεί τι γένος ζῴων καθεύδειν ἢ ἀεί τι ἐγρηγορέναι.
ἔτι ὅσων ἔστι τι ἔργον κατὰ φύσιν, ὅταν ὑπερβάλλῃ
τὸν χρόνον ὅσον δύναταί τι ποιεῖν, ἀνάγκη ἀδυνατεῖν,
οἷον τὰ ὄμματα ὁρῶντα, καὶ παύεσθαι τοῦτο ποιοῦντα, ὁμοίως
δὲ καὶ χεῖρα καὶ ἄλλο πᾶν οὗ ἔστι τι ἔργον. εἰ δή τινός
30 ἐστιν ἔργον τὸ αἰσθάνεσθαι, καὶ τοῦτο, ἂν ὑπερβάλλῃ ὅσον
ἦν χρόνον δυνάμενον αἰσθάνεσθαι συνεχῶς, ἀδυνατήσει καὶ
οὐκέτι τοῦτο ποιήσει. εἰ τοίνυν τὸ ἐγρηγορέναι ὥρισται τῷ λελύσθαι
1If waking, then, 5consists in nothing else than the exercise of sense-perception, the inference is clear, that the organ, in virtue of which animals perceive, is that by which they wake, when they are awake, or sleep, when they are awake, or sleep, when they are asleep.
But since the exercise of sense-perception does not belong to soul or body exclusively, then (since the subject of actuality is in every case identical with that of potentiality, and what is called sense-perception, as actuality, is a movement of the soul through the body) it is clear that 10its affection is not an affection of soul exclusively, and that a soulless body has not the potentiality of perception. [Thus sleep and waking are not attributes of pure intelligence, on the one hand, or of inanimate bodies, on the other.]
Now, whereas we have already elsewhere distinguished what are called the parts of the soul, and whereas the nutrient is, in all living bodies, capable of existing without the other parts, while none of the others can exist without the nutrient; it is clear that sleep and waking are not affections of 15such living things as partake only of growth and decay, e.g. not of plants, because these have not the faculty of sense-perception, whether or not this be capable of separate existence; in its potentiality, indeed, and in its relationships, it is separable.
Likewise it is clear that [of those which either sleep or wake] there is no animal which is always awake or always asleep, 20but that both these affections belong [alternately] to the same animals. For if there be an animal not endued with sense-perception, it is impossible that this should either sleep or wake; since both these are affections of the activity of the primary faculty of sense-perception. But it is equally impossible also that either of these two affections should perpetually attach itself to the same animal, e.g. that 25some species of animal should be always asleep or always awake, without intermission; for all organs which have a natural function must lose power when they work beyond the natural time-limit of their working period; for instance, the eyes [must lose power] from too long continued seeing, and must give it up; and so it is withthe hand and every other member which has a function. Now, 30if sense-perception is the function of a special organ, this also, if it continues perceiving beyond the appointed time-limit of its continuous working period, will lose its power, and will do its work no longer.
But since the exercise of sense-perception does not belong to soul or body exclusively, then (since the subject of actuality is in every case identical with that of potentiality, and what is called sense-perception, as actuality, is a movement of the soul through the body) it is clear that 10its affection is not an affection of soul exclusively, and that a soulless body has not the potentiality of perception. [Thus sleep and waking are not attributes of pure intelligence, on the one hand, or of inanimate bodies, on the other.]
Now, whereas we have already elsewhere distinguished what are called the parts of the soul, and whereas the nutrient is, in all living bodies, capable of existing without the other parts, while none of the others can exist without the nutrient; it is clear that sleep and waking are not affections of 15such living things as partake only of growth and decay, e.g. not of plants, because these have not the faculty of sense-perception, whether or not this be capable of separate existence; in its potentiality, indeed, and in its relationships, it is separable.
Likewise it is clear that [of those which either sleep or wake] there is no animal which is always awake or always asleep, 20but that both these affections belong [alternately] to the same animals. For if there be an animal not endued with sense-perception, it is impossible that this should either sleep or wake; since both these are affections of the activity of the primary faculty of sense-perception. But it is equally impossible also that either of these two affections should perpetually attach itself to the same animal, e.g. that 25some species of animal should be always asleep or always awake, without intermission; for all organs which have a natural function must lose power when they work beyond the natural time-limit of their working period; for instance, the eyes [must lose power] from too long continued seeing, and must give it up; and so it is withthe hand and every other member which has a function. Now, 30if sense-perception is the function of a special organ, this also, if it continues perceiving beyond the appointed time-limit of its continuous working period, will lose its power, and will do its work no longer.
454b
1 τὴν αἴσθησιν, τῶν δ' ἐναντίων τῶν μὲν ἀνάγκη θάτερον
ἀεὶ παρεῖναι τῶν δ' οὔ, τῷ δ' ἐγρηγορέναι τὸ καθεύδειν ἐναντίον,
καὶ ἀναγκαῖον ἅπαντι θάτερον ὑπάρχειν, ἀναγκαῖον ἂν εἴη καθεύδειν.
εἰ οὖν τὸ τοιοῦτον πάθος ὕπνος, τοῦτο δ' ἐστὶν ἀδυναμία
5 δι' ὑπερβολὴν τοῦ ἐγρηγορέναι, ἡ δὲ τοῦ ἐγρηγορέναι
ὑπερβολὴ ὁτὲ μὲν νοσώδης ὁτὲ δὲ ἄνευ νόσου γίγνεται, ὥστε
καὶ ἡ ἀδυναμία καὶ ἡ διάλυσις ὡσαύτως ἔσται, ἀνάγκη
πᾶν τὸ ἐγρηγορὸς ἐνδέχεσθαι καθεύδειν· ἀδύνατον γὰρ ἀεὶ
ἐνεργεῖν. ὁμοίως δὲ οὐδὲ καθεύδειν οὐδὲν ἀεὶ ἐνδέχεται. ὁ γὰρ
10 ὕπνος πάθος τι τοῦ αἰσθητικοῦ μορίου ἐστίν, οἷον δεσμός τις καὶ
ἀκινησία, ὥστ' ἀνάγκη πᾶν τὸ καθεῦδον ἔχειν τὸ αἰσθητικὸν μόριον.
αἰσθητικὸν δὲ τὸ δυνατὸν αἰσθάνεσθαι κατ' ἐνέργειαν·
ἐνεργεῖν δὲ τῇ αἰσθήσει κυρίως καὶ ἁπλῶς ἀδύνατον καθεῦδον
ἅμα· διὸ ἀναγκαῖον ὕπνον πάντα ἐγερτὸν εἶναι. τὰ μὲν
15 οὖν ἄλλα σχεδὸν ἅπαντα δῆλα κοινωνοῦνθ' ὕπνου, καὶ πλωτὰ
καὶ πτηνὰ καὶ πεζά· καὶ γὰρ τὰ τῶν ἰχθύων γένη πάντα
καὶ τὰ τῶν μαλακίων ὦπται καθεύδοντα, καὶ τἆλλα πάντα
ὅσαπερ ἔχει ὀφθαλμούς· καὶ γὰρ τὰ σκληρόφθαλμα φανερὰ
καὶ τὰ ἔντομα κοιμώμενα· βραχύυπνα δὲ τὰ τοιαῦτα
20 πάντα, διὸ καὶ λάθοι ἄν τινα πολλάκις πότερον μετέχουσι
τοῦ καθεύδειν ἢ οὔ. τῶν δ' ὀστρακοδέρμων κατὰ μὲν τὴν αἴσθησιν
οὐδέ πω γέγονε φανερὸν εἰ καθεύδουσιν· εἰ δέ τῳ πιθανὸς
ὁ λεχθεὶς λόγος, τοῦτο πεισθήσεται. ὅτι μὲν οὖν ὕπνου κοινωνεῖ
τὰ ζῷα πάντα, φανερὸν ἐκ τούτων. τῷ γὰρ αἴσθησιν
25 ἔχειν ὥρισται τὸ ζῷον, τῆς δ' αἰσθήσεως τρόπον τινὰ τὴν μὲν
ἀκινησίαν καὶ οἷον δεσμὸν τὸν ὕπνον εἶναί φαμεν, τὴν δὲ
λύσιν καὶ τὴν ἄνεσιν ἐγρήγορσιν. τῶν δὲ φυτῶν οὐδὲν οἷόν τε
κοινωνεῖν οὐδετέρου τούτων τῶν παθημάτων· ἄνευ μὲν γὰρ αἰσθήσεως
οὐχ ὑπάρχει οὔτε ὕπνος οὔτε ἐγρήγορσις· οἷς δ' αἴσθησις
30 ὑπάρχει, καὶ τὸ λυπεῖσθαι καὶ τὸ χαίρειν· οἷς δὲ
ταῦτα, καὶ ἐπιθυμία· τοῖς δὲ φυτοῖς οὐδὲν ὑπάρχει τούτων.
σημεῖον δ' ὅτι καὶ τὸ ἔργον τὸ αὑτοῦ ποιεῖ τὸ θρεπτικὸν
1Accordingly, if the waking period is determined by this fact, that in it sense-perception is free; if in the case of some contraries one of the two must be present, while in the case of others this is not necessary; if waking is the contrary of sleeping, and one of these two must be present to every animal: it must follow that the state of sleeping is necessary. Finally, if such affection is Sleep, and this is a state of powerlessness 5arising from excess of waking, and excess of waking is in its origin sometimes morbid, sometimes not, so that the powerlessness or dissolution of activity will be so or not; it is inevitable that every creature which wakes must also be capable of sleeping, since it is impossible that it should continue actualizing its powers perpetually.
So, also, it is impossible for any animal to continue always sleeping. 10For sleep is an affection of the organ of sense-perception--a sort of tie or inhibition of function imposed on it, so that every creature that sleeps must needs have the organ of sense-perception. Now, that alone which is capable of sense-perception in actuality has the faculty of sense-perception; but to realize this faculty, in the proper and unqualified sense, is impossible while one is asleep. All sleep, therefore, must be susceptible of awakening. Accordingly, 15almost all other animals are clearly observed to partake in sleep, whether they are aquatic, aerial, or terrestrial, since fishes of all kinds, and molluscs, as well as all others which have eyes, have been seen sleeping. 'Hard-eyed' creatures and insects manifestly assume the posture of sleep; but the sleep of all such creatures is of brief duration, 20so that often it might well baffle one's observation to decide whether they sleep or not. Of testaceous animals, on the contrary, no direct sensible evidence is as yet forthcoming to determine whether they sleep, but if the above reasoning be convincing to any one, he who follows it will admit this [viz. that they do so.]
That, therefore, all animals sleep may be gathered from these considerations. For 25an animal is defined as such by its possessing sense-perception; and we assert that sleep is, in a certain way, an inhibition of function, or, as it were, a tie, imposed on sense-perception, while its loosening or remission constitutes the being awake. But no plant can partake in either of these affections, for without sense-perception there is neither sleeping nor waking. But creatures which have sense-perception 30have likewise the feeling of pain and pleasure, while those which have these have appetite as well; but plants have none of these affections.
So, also, it is impossible for any animal to continue always sleeping. 10For sleep is an affection of the organ of sense-perception--a sort of tie or inhibition of function imposed on it, so that every creature that sleeps must needs have the organ of sense-perception. Now, that alone which is capable of sense-perception in actuality has the faculty of sense-perception; but to realize this faculty, in the proper and unqualified sense, is impossible while one is asleep. All sleep, therefore, must be susceptible of awakening. Accordingly, 15almost all other animals are clearly observed to partake in sleep, whether they are aquatic, aerial, or terrestrial, since fishes of all kinds, and molluscs, as well as all others which have eyes, have been seen sleeping. 'Hard-eyed' creatures and insects manifestly assume the posture of sleep; but the sleep of all such creatures is of brief duration, 20so that often it might well baffle one's observation to decide whether they sleep or not. Of testaceous animals, on the contrary, no direct sensible evidence is as yet forthcoming to determine whether they sleep, but if the above reasoning be convincing to any one, he who follows it will admit this [viz. that they do so.]
That, therefore, all animals sleep may be gathered from these considerations. For 25an animal is defined as such by its possessing sense-perception; and we assert that sleep is, in a certain way, an inhibition of function, or, as it were, a tie, imposed on sense-perception, while its loosening or remission constitutes the being awake. But no plant can partake in either of these affections, for without sense-perception there is neither sleeping nor waking. But creatures which have sense-perception 30have likewise the feeling of pain and pleasure, while those which have these have appetite as well; but plants have none of these affections.
455a
1 μόριον ἐν τῷ καθεύδειν μᾶλλον ἢ ἐν τῷ ἐγρηγορέναι·
τρέφεται γὰρ καὶ αὐξάνεται τότε μᾶλλον, ὡς οὐδὲν προςδεόμενα
πρὸς ταῦτα τῆς αἰσθήσεως.
1A mark of this is that the nutrient part does its own work better when (the animal) is asleep than when it is awake. Nutrition and growth are then especially promoted, a fact which implies that creatures do not need sense-perception to assist these processes.
Chapter 2 (455a4–456a29)
Διὰ τί δὲ καθεύδει καὶ ἐγρήγορε καὶ διὰ ποίαν τινὰ
5 αἴσθησιν ἢ ποίας, εἰ διὰ πλείους, σκεπτέον. ἐπεὶ δ' ἔνια μὲν
τῶν ζῴων ἔχει τὰς αἰσθήσεις πάσας, ἔνια δ' οὐκ ἔχει, οἷον
ὄψιν, τὴν δ' ἁφὴν καὶ τὴν γεῦσιν ἅπαντα ἔχει, πλὴν εἴ τι
τῶν ζῴων ἀτελές (εἴρηται δὲ περὶ αὐτῶν ἐν τοῖς Περὶ ψυχῆς),
ἀδύνατον δ' ἐστὶν ἁπλῶς ὁποιανοῦν αἴσθησιν αἰσθάνεσθαι
10 τὸ καθεῦδον ζῷον, φανερὸν ὅτι πάσαις ἀναγκαῖον ὑπάρχειν
τὸ αὐτὸ πάθος ἐν τῷ καλουμένῳ ὕπνῳ· εἰ γὰρ τῇ μέν, τῇ δὲ
μή, ταύτῃ καθεῦδον αἰσθήσεται, τοῦτο δ' ἀδύνατον. ἐπεὶ δ'
ὑπάρχει καθ' ἑκάστην αἴσθησιν τὸ μέν τι ἴδιον, τὸ δέ τι κοινόν,
ἴδιον μὲν οἷον τῇ ὄψει τὸ ὁρᾶν, τῇ δ' ἀκοῇ τὸ ἀκούειν,
15 καὶ ταῖς ἄλλαις ἑκάστῃ κατὰ τὸν αὐτὸν τρόπον, ἔστι δέ τις καὶ
κοινὴ δύναμις ἀκολουθοῦσα πάσαις, ᾗ καὶ ὅτι ὁρᾷ καὶ ἀκούει
αἰσθάνεται (οὐ γὰρ δὴ τῇ γε ὄψει ὁρᾷ ὅτι ὁρᾷ, καὶ κρίνει
δὴ καὶ δύναται κρίνειν ὅτι ἕτερα τὰ γλυκέα τῶν λευκῶν
οὔτε γεύσει οὔτε ὄψει οὔτε ἀμφοῖν, ἀλλά τινι κοινῷ μορίῳ
20 τῶν αἰσθητηρίων ἁπάντων· ἔστι μὲν γὰρ μία αἴσθησις, καὶ
τὸ κύριον αἰσθητήριον ἕν, τὸ δ' εἶναι αἰσθήσει τοῦ γένους ἑκάστου
ἕτερον, οἷον ψόφου καὶ χρώματος), τοῦτο δ' ἅμα τῷ
ἁπτικῷ μάλιστα ὑπάρχει (τοῦτο μὲν γὰρ χωρίζεται τῶν
ἄλλων αἰσθητηρίων, τὰ δ' ἄλλα τούτου ἀχώριστα, εἴρηται δὲ
25 περὶ αὐτῶν ἐν τοῖς Περὶ ψυχῆς θεωρήμασιν), φανερὸν τοίνυν
ὅτι τούτου ἐστὶ πάθος ἡ ἐγρήγορσις καὶ ὁ ὕπνος. διὸ καὶ πᾶσιν
ὑπάρχει τοῖς ζῴοις· καὶ γὰρ ἡ ἁφὴ μόνη πᾶσιν· εἰ
γὰρ τῷ πάσας τι πεπονθέναι τὰς αἰσθήσεις ἐγίγνετο τὸ καθεύδειν,
ἄτοπον εἰ αἷς οὔτε ἀνάγκη οὔτε δυνατὸν τρόπον τινὰ
30 ἐνεργεῖν ἅμα, ταύτας ἀναγκαῖον ἀργεῖν ἅμα καὶ ἀκινητίζειν·
τοὐναντίον γὰρ εὐλογώτερον συνέβαινεν ἂν αὐταῖς, τὸ
μὴ ἅμα ἠρεμεῖν. ὡς δὲ νῦν λέγομεν, εὐλόγως ἔχει καὶ
περὶ τούτων· τοῦ γὰρ κυρίου τῶν ἄλλων πάντων αἰσθητηρίου,
καὶ πρὸς ὃ συντείνει τἆλλα, πεπονθότος τι συμπάσχειν ἀναγκαῖον
4We must now proceed to inquire into the cause why one sleeps and wakes, and into the particular nature of 5the sense-perception, or sense-perceptions, if there be several, on which these affections depend. Since, then, some animals possess all the modes of sense-perception, and some not all, not, for example, sight, while all possess touch and taste, except such animals as are imperfectly developed, a class of which we have already treated in our work on the soul; and since 10an animal when asleep is unable to exercise, in the simple sense any particular sensory faculty whatever, it follows that in the state called sleep the same affection must extend to all the special senses; because, if it attaches itself to one of them but not to another, then an animal while asleep may perceive with the latter; but this is impossible.
Now, since every sense has something peculiar, and also something common; peculiar, as, e.g. seeing is to the sense of sight, hearing to the auditory sense, 15and so on with the other senses severally; while all are accompanied by a common power, in virtue whereof a person perceives that he sees or hears (for, assuredly, it is not by the special sense of sight that one sees that he sees; and it is not by mere taste, or sight, or both together that one discerns, and has the faculty of discerning, that sweet things are different from white things, 20but by a faculty connected in common with all the organs of sense; for there is one sensory function, and the controlling sensory faculty is one, though differing as a faculty of perception in relation to each genus of sensibles, e.g. sound or colour); and since this [common sensory activity] subsists in association chiefly with the faculty of touch (for this can exist apart from all the other organs of sense, but none of them can exist apart from it-a subject of which we have treated 25in our speculations concerning the Soul); it is therefore evident that waking and sleeping are an affection of this common and controlling organ of sense-perception . This explainswhy they belong to all animals, for touch [with which this common organ is chiefly connected], alone, [is common] to all [animals].
For if sleeping were caused by the special senses having each and all undergone some affection, it would be strange that these senses, for which it is neither necessary nor in a manner possible to realize their powers simultaneously, 30should necessarily all go idle and become motionless simultaneously. For the contrary experience, viz. that they should not go to rest altogether, would have been more reasonably anticipated. But, according to the explanation just given, all is quite clear regarding those also.
Now, since every sense has something peculiar, and also something common; peculiar, as, e.g. seeing is to the sense of sight, hearing to the auditory sense, 15and so on with the other senses severally; while all are accompanied by a common power, in virtue whereof a person perceives that he sees or hears (for, assuredly, it is not by the special sense of sight that one sees that he sees; and it is not by mere taste, or sight, or both together that one discerns, and has the faculty of discerning, that sweet things are different from white things, 20but by a faculty connected in common with all the organs of sense; for there is one sensory function, and the controlling sensory faculty is one, though differing as a faculty of perception in relation to each genus of sensibles, e.g. sound or colour); and since this [common sensory activity] subsists in association chiefly with the faculty of touch (for this can exist apart from all the other organs of sense, but none of them can exist apart from it-a subject of which we have treated 25in our speculations concerning the Soul); it is therefore evident that waking and sleeping are an affection of this common and controlling organ of sense-perception . This explainswhy they belong to all animals, for touch [with which this common organ is chiefly connected], alone, [is common] to all [animals].
For if sleeping were caused by the special senses having each and all undergone some affection, it would be strange that these senses, for which it is neither necessary nor in a manner possible to realize their powers simultaneously, 30should necessarily all go idle and become motionless simultaneously. For the contrary experience, viz. that they should not go to rest altogether, would have been more reasonably anticipated. But, according to the explanation just given, all is quite clear regarding those also.
455b
1 καὶ τὰ λοιπὰ πάντα, ἐκείνων δέ τινος ἀδυνατοῦντος
οὐκ ἀνάγκη τοῦτ' ἀδυνατεῖν. φανερὸν δὲ ἐκ πολλῶν ὅτι
οὐκ ἐν τῷ τὰς αἰσθήσεις ἀργεῖν καὶ μὴ χρῆσθαι αὐταῖς ὁ
ὕπνος, οὐδ' ἐν τῷ μὴ δύνασθαι αἰσθάνεσθαι (καὶ γὰρ ἐν ταῖς
5 λειποψυχίαις τοιοῦτόν τι συμβαίνει· ἀδυναμία γὰρ αἰσθήσεως
ἡ λειποψυχία, γίγνονται δὲ καὶ ἔκνοιαί τινες τοιαῦται· ἔτι
δ' οἱ τὰς ἐν τῷ αὐχένι φλέβας καταλαμβανόμενοι ἀναίσθητοι
γίγνονται), ἀλλ' ὅταν ἡ ἀδυναμία τῆς χρήσεως μήτ'
ἐν τῷ τυχόντι αἰσθητηρίῳ, μήτε δι' ἣν ἔτυχεν αἰτίαν, ἀλλά,
10 καθάπερ εἴρηται νῦν, ἐν τῷ πρώτῳ ᾧ αἰσθάνεται πάντων·
ὅταν μὲν γὰρ τοῦτ' ἀδυνατήσῃ, ἀνάγκη καὶ τοῖς αἰσθητηρίοις
πᾶσιν ἀδυνατεῖν αἰσθέσθαι, ὅταν δ' ἐκείνων τι, οὐκ ἀνάγκη
τούτῳ. δι' ἣν δ' αἰτίαν συμβαίνει τὸ καθεύδειν, καὶ ποῖόν τι
τὸ πάθος ἐστί, λεκτέον. ἐπεὶ δὲ τρόποι πλείους τῆς αἰτίας
15 (καὶ γὰρ τὸ τίνος ἕνεκεν, καὶ ὅθεν ἡ ἀρχὴ τῆς κινήσεως, καὶ
τὴν ὕλην καὶ τὸν λόγον αἴτιον εἶναί φαμεν), πρῶτον μὲν
οὖν ἐπειδὴ λέγομεν τὴν φύσιν ἕνεκά του ποιεῖν, τοῦτο δὲ ἀγαθόν
τι, τὴν δ' ἀνάπαυσιν παντὶ τῷ πεφυκότι κινεῖσθαι, μὴ
δυναμένῳ δ' ἀεὶ καὶ συνεχῶς κινεῖσθαι μεθ' ἡδονῆς, ἀναγκαῖον
20 εἶναι καὶ ὠφέλιμον, τῷ δὲ ὕπνῳ αὐτῇ τῇ ἀληθείᾳ
προσάπτουσι τὴν μεταφορὰν ταύτην ὡς ἀναπαύσει ὄντι—
ὥστε σωτηρίας ἕνεκα τῶν ζῴων ὑπάρχει. ἡ δ' ἐγρήγορσις
τέλος· τὸ γὰρ αἰσθάνεσθαι καὶ τὸ φρονεῖν πᾶσι τέλος οἷς
ὑπάρχει θάτερον αὐτῶν. βέλτιστα γὰρ ταῦτα, τὸ δὲ τέλος
25 βέλτιστον. ἔτι δὲ ἀναγκαῖον ἑκάστῳ τῶν ζῴων ὑπάρχειν τὸν
ὕπνον. λέγω δ' ἐξ ὑποθέσεως τὴν ἀνάγκην, ὅτι εἰ ζῷον ἔσται
ἔχον τὴν αὑτοῦ φύσιν, ἐξ ἀνάγκης τινὰ ὑπάρχειν αὐτῷ δεῖ,
καὶ τούτων ὑπαρχόντων ἕτερα ὑπάρχειν. ἔτι δὲ ποίας κινήσεως
καὶ πράξεως ἐν τοῖς σώμασι γιγνομένης συμβαίνει τό
30 τε ἐγρηγορέναι καὶ τὸ καθεύδειν τοῖς ζῴοις, μετὰ ταῦτα
λεκτέον. τοῖς μὲν οὖν ἄλλοις ζῴοις καθάπερ τοῖς ἐναίμοις
ὑποληπτέον εἶναι τὰ αἴτια τοῦ πάθους ἢ ταὐτὰ ἢ τὰ ἀνάλογον,
τοῖς δ' ἐναίμοις ἅπερ τοῖς ἀνθρώποις· ὥστε ἐκ τούτων
πάντα θεωρητέον. ὅτι μὲν οὖν ἡ τῆς αἰσθήσεως ἀρχὴ γίγνεται
1For, when the sense organ which controls all the others, and to which all the others are tributary, has been in some way affected, that these others should be all affected at the same time is inevitable, whereas, if one of the tributaries becomes powerless, that the controlling organ should also become powerless need in no wise follow.
It is indeed evident from many considerations that sleep does not consist in the mere fact that the special senses do not function or that one does not employ them; and that it does not consist merely in an inability to exercise the sense-perceptions; 5for such is what happens in cases of swooning. A swoon means just such impotence of perception, and certain other cases of unconsciousness also are of this nature. Moreover, persons who have the bloodvessels in the neck compressed become insensible. But sleep supervenes when such incapacity of exercise has neither arisen in some casual organ of sense, nor from some chance cause, but when, 10as has been just stated, it has its seat in the primary organ with which one perceives objects in general. For when this has become powerless all the other sensory organs also must lack power to perceive; but when one of them has become powerless, it is not necessary for this also to lose its power.
We must next state the cause to which it is due, and its quality as an affection. Now, since there are several types of cause (15for we assign equally the 'final', the 'efficient', the 'material', and the 'formal' as causes), in the first place, then, as we assert that Nature operates for the sake of an end, and that this end is a good; and that to every creature which is endowed by nature with the power to move, but cannot with pleasure to itself move always and continuously, 20rest is necessary and beneficial; and since, taught by experience, men apply to sleep this metaphorical term, calling it a 'rest' [from the strain of movement implied in sense-perception]: we conclude that its end is the conservation of animals. But the waking state is for an animal its highest end, since the exercise of sense-perception or of thought is the highest end for all beings to which either of these appertains; inasmuch as these are best, and the highest end is what is best: 25whence it follows that sleep belongs of necessity to each animal. I use the term 'necessity' in its conditional sense, meaning that if an animal is to exist and have its own proper nature, it must have certain endowments; and, if these are to belong to it, certain others likewise must belong to it as their condition.
The next question to be discussed is that of the kind of movement or action, taking place within their bodies, 30from which the affection of waking or sleeping arises in animals. Now, we must assume that the causes of this affection in all other animals are identical with, or analogous to, those which operate in sanguineous animals; and that the causes operating in sanguineous animals generally are identical with those operating in man.
It is indeed evident from many considerations that sleep does not consist in the mere fact that the special senses do not function or that one does not employ them; and that it does not consist merely in an inability to exercise the sense-perceptions; 5for such is what happens in cases of swooning. A swoon means just such impotence of perception, and certain other cases of unconsciousness also are of this nature. Moreover, persons who have the bloodvessels in the neck compressed become insensible. But sleep supervenes when such incapacity of exercise has neither arisen in some casual organ of sense, nor from some chance cause, but when, 10as has been just stated, it has its seat in the primary organ with which one perceives objects in general. For when this has become powerless all the other sensory organs also must lack power to perceive; but when one of them has become powerless, it is not necessary for this also to lose its power.
We must next state the cause to which it is due, and its quality as an affection. Now, since there are several types of cause (15for we assign equally the 'final', the 'efficient', the 'material', and the 'formal' as causes), in the first place, then, as we assert that Nature operates for the sake of an end, and that this end is a good; and that to every creature which is endowed by nature with the power to move, but cannot with pleasure to itself move always and continuously, 20rest is necessary and beneficial; and since, taught by experience, men apply to sleep this metaphorical term, calling it a 'rest' [from the strain of movement implied in sense-perception]: we conclude that its end is the conservation of animals. But the waking state is for an animal its highest end, since the exercise of sense-perception or of thought is the highest end for all beings to which either of these appertains; inasmuch as these are best, and the highest end is what is best: 25whence it follows that sleep belongs of necessity to each animal. I use the term 'necessity' in its conditional sense, meaning that if an animal is to exist and have its own proper nature, it must have certain endowments; and, if these are to belong to it, certain others likewise must belong to it as their condition.
The next question to be discussed is that of the kind of movement or action, taking place within their bodies, 30from which the affection of waking or sleeping arises in animals. Now, we must assume that the causes of this affection in all other animals are identical with, or analogous to, those which operate in sanguineous animals; and that the causes operating in sanguineous animals generally are identical with those operating in man.
456a
1 ἀπὸ τοῦ αὐτοῦ μέρους τοῖς ζῴοις ἀφ' οὗπερ καὶ ἡ τῆς κινήσεως,
διώρισται πρότερον ἐν ἑτέροις. αὕτη δέ ἐστι τριῶν διωρισμένων
τόπων ὁ μέσος κεφαλῆς καὶ τῆς κάτω κοιλίας. τοῖς μὲν
οὖν ἐναίμοις τοῦτ' ἐστὶ τὸ περὶ τὴν καρδίαν μέρος. πάντα γὰρ
5 τὰ ἔναιμα καρδίαν ἔχει, καὶ ἡ ἀρχὴ τῆς κινήσεως καὶ τῆς
αἰσθήσεως τῆς κυρίας ἐντεῦθέν ἐστιν. τῆς μὲν οὖν κινήσεως
φανερὸν ὅτι καὶ ἡ τοῦ πνεύματος ἀρχὴ καὶ ὅλως ἡ τῆς καταψύξεώς
ἐστιν ἐνταῦθα, καὶ τὸ ἀναπνεῖν τε καὶ τὸ τῷ ὑγρῷ
καταψύχεσθαι πρός γε τὴν σωτηρίαν τοῦ ἐν τούτῳ μορίῳ θερμοῦ
10 ἡ φύσις πεπόρικεν· ῥηθήσεται δὲ περὶ αὐτῆς ὕστερον καθ'
αὑτήν. τοῖς δὲ ἀναίμοις καὶ τοῖς ἐντόμοις καὶ μὴ δεχομένοις
πνεῦμα ἐν τῷ ἀνάλογον τὸ σύμφυτον πνεῦμα ἀναφυσώμενον
καὶ συνιζάνον φαίνεται. δῆλον δὲ τοῦτο ἐπὶ τῶν
ὁλοπτέρων, οἷον σφηκῶν καὶ μελιττῶν, καὶ ἐν ταῖς μυίαις
15 καὶ ὅσα τοιαῦτα. ἐπεὶ δὲ κινεῖν μέν τι ἢ ποιεῖν ἄνευ ἰσχύος
ἀδύνατον, ἰσχὺν δὲ ποιεῖ ἡ τοῦ πνεύματος κάθεξις, τοῖς μὲν
εἰσφερομένοις ἡ θύραθεν, τοῖς δὲ μὴ ἀναπνέουσιν ἡ σύμφυτος
(διὸ καὶ βομβοῦντα φαίνεται τὰ πτερωτά, ὅταν κινῆται,
τῇ τρίψει τοῦ πνεύματος προσπίπτοντος πρὸς τὸ ὑπόζωμα
20 τῶν ὁλοπτέρων), κινεῖται δὲ πᾶν αἰσθήσεώς τινος γενομένης,
ἢ οἰκείας ἢ ἀλλοτρίας, ἐν τῷ πρώτῳ αἰσθητηρίῳ—εἰ δή ἐστιν
ὁ ὕπνος καὶ ἡ ἐγρήγορσις πάθη τοῦ μορίου τούτου, ἐν ᾧ μὲν
τόπῳ καὶ ἐν ᾧ μορίῳ πρώτῳ γίγνεται ὁ ὕπνος καὶ ἡ ἐγρήγορσις,
φανερόν. κινοῦνται δ' ἔνιοι καθεύδοντες καὶ ποιοῦσι
25 πολλὰ ἐγρηγορικά, οὐ μέντοι ἄνευ φαντάσματος καὶ αἰσθήσεώς
τινος· τὸ γὰρ ἐνύπνιόν ἐστιν αἴσθημα τρόπον τινά·
λεκτέον δὲ περὶ αὐτῶν ὕστερον. διότι δὲ τὰ μὲν ἐνύπνια
μνημονεύουσιν ἐγερθέντες, τὰς δ' ἐγρηγορικὰς πράξεις ἀμνημονοῦσιν,
ἐν τοῖς Προβληματικοῖς εἴρηται.
1Hence we must consider the entire subject in the light of these instances [afforded by sanguineous animals, especially man]. Now, it has been definitely settled already in another work that sense-perception in animals originates ill the same part of the organism in which movement originates. This locus of origination is one of three determinate loci, viz. that which lies midway between the head and the abdomen. This is sanguineous animals is the region of the heart; 5for all sanguineous animals have a heart; and from this it is that both motion and the controlling sense-perception originate. Now, as regards movement, it is obvious that that of breathing and of the cooling process generally takes its rise there; and it is with a view to the conservation of the [due amount of] heat in this part that nature has formed as she has both the animals which respire, and those which cool themselves by moisture. 10Of this [cooling process] per se we shall treat hereafter. In bloodless animals, and insects, and such as do not respire, the 'connatural spirit' is seen alternately puffed up and subsiding in the part which is in them analogous [to the region of the heart in sanguineous animals]. This is clearly observable in the holoptera [insects with undivided wings] as wasps and bees; also in flies and such creatures. 15And since to move anything, or do anything, is impossible without strength, and holding the breath produces strength-in creatures which inhale, the holding of that breath which comes from without, but, in creatures which do not respire, of that which is connatural (which explains why winged insects of the class holoptera, when they move, are perceived to make a humming noise, due to the friction of the connatural spirit colliding with the diaphragm); 20and since movement is, in every animal, attended with some sense-perception, either internal or external, in the primary organ of sense, [we conclude] accordingly that if sleeping and waking are affections of this organ, the place in which, or the organ in which, sleep and waking originate, is self-evident [being that in which movement and sense-perception originate, viz. the heart].
Some persons move in their sleep, and 25perform many acts like waking acts, but not without a phantasm or an exercise of sense-perception; for a dream is in a certain way a sense-impression. But of them we have to speak later on. Why it is that persons when aroused remember their dreams, but do not remember these acts which are like waking acts, has been already explained in the work 'Of Problems'.
Some persons move in their sleep, and 25perform many acts like waking acts, but not without a phantasm or an exercise of sense-perception; for a dream is in a certain way a sense-impression. But of them we have to speak later on. Why it is that persons when aroused remember their dreams, but do not remember these acts which are like waking acts, has been already explained in the work 'Of Problems'.
Chapter 3 (456a30–458a32)
30 Ἐχόμενον δὲ τῶν εἰρημένων ἐστὶν ἐπελθεῖν τίνων γιγνομένων
καὶ πόθεν ἡ ἀρχὴ τοῦ πάθους γίγνεται, τοῦ τ' ἐγρηγορέναι
καὶ τοῦ καθεύδειν. φανερὸν δὴ ὅτι ἐπεὶ ἀναγκαῖον
τῷ ζῴῳ, ὅταν αἴσθησιν ἔχῃ, τότε πρῶτον τροφήν τε λαμβάνειν
καὶ αὔξησιν, τροφὴ δ' ἐστὶ πᾶσιν ἡ ἐσχάτη τοῖς μὲν
35 ἐναίμοις ἡ τοῦ αἵματος φύσις, τοῖς δ' ἀναίμοις τὸ ἀνάλογον,
30The point for consideration next in order to the preceding is:-What are the processes in which the affection of waking and sleeping originates, and whence do they arise? Now, since it is when it has sense-perception that an animal must first take food and receive growth, and in all cases food in its ultimate form is, 35in sanguineous animals, the natural substance blood, or, in bloodless animals, that which is analogous to this; and since the veins are the place of the blood, while the origin of these is the heart-an assertion which is proved by anatomy-it is manifest that, when the external nutriment enters the parts fitted for its reception, the evaporation arising from it enters into the veins, and there, undergoing a change, is converted into blood, and makes its way to their source [the heart].
456b
1 τόπος δὲ τοῦ αἵματος αἱ φλέβες, τούτων δ' ἀρχὴ ἡ καρδία
(φανερὸν δὲ τὸ λεχθὲν ἐκ τῶν ἀνατομῶν)—τῆς μὲν οὖν θύραθεν
τροφῆς εἰσιούσης εἰς τοὺς δεκτικοὺς τόπους γίγνεται ἡ ἀναθυμίασις
εἰς τὰς φλέβας, ἐκεῖ δὲ μεταβάλλουσα ἐξαιματοῦται
5 καὶ πορεύεται ἐπὶ τὴν ἀρχήν. εἴρηται δὲ περὶ τούτων
ἐν τοῖς Περὶ τροφῆς· νῦν δὲ ἀναληπτέον ὑπὲρ αὐτῶν τούτου
χάριν, ὅπως τὰς ἀρχὰς τῆς κινήσεως θεωρήσωμεν, καὶ τί
πάσχοντος τοῦ μορίου τοῦ αἰσθητικοῦ συμβαίνει ἡ ἐγρήγορσις
καὶ ὁ ὕπνος. οὐ γάρ ἐστιν ὁ ὕπνος ἡτισοῦν ἀδυναμία τοῦ αἰσθητικοῦ,
10 καθάπερ εἴρηται· καὶ γὰρ ἔκνοια καὶ πνιγμός τις
καὶ λειποψυχία ποιεῖ τὴν τοιαύτην ἀδυναμίαν. ἤδη δὲ γεγένηταί
τισι καὶ φαντασία λειποψυχήσασιν ἰσχυρῶς. τοῦτο
μὲν οὖν ἔχει τινὰ ἀπορίαν· εἰ γὰρ ἐνδέχεται καταδαρθεῖν
τὸν λειποψυχήσαντα, ἐνδέχοιτ' ἂν ἐνύπνιον εἶναι καὶ τὸ
15 φάντασμα. πολλὰ δ' ἐστὶν ἃ λέγουσιν οἱ σφόδρα λειποψυχήσαντες
καὶ δόξαντες τεθνάναι· περὶ ὧν τὸν αὐτὸν λόγον
ὑποληπτέον εἶναι πάντων. ἀλλὰ γάρ, ὥσπερ εἴπομεν, οὐκ
ἔστιν ὁ ὕπνος ἀδυναμία πᾶσα τοῦ αἰσθητικοῦ, ἀλλ' ἐκ τῆς
περὶ τὴν τροφὴν ἀναθυμιάσεως γίγνεται τὸ πάθος τοῦτο·
20 ἀνάγκη γὰρ τὸ ἀναθυμιώμενον μέχρι του ὠθεῖσθαι, εἶτ'
ἀντιστρέφειν καὶ μεταβάλλειν καθάπερ εὔριπον. τὸ δὲ θερμὸν
ἑκάστου τῶν ζῴων πρὸς τὸ ἄνω πέφυκε φέρεσθαι· ὅταν
δ' ἐν τοῖς ἄνω τόποις γένηται, ἀθρόον πάλιν ἀντιστρέφει
καὶ καταφέρεται. διὸ μάλιστα γίγνονται ὕπνοι ἀπὸ τῆς τροφῆς·
25 ἀθρόον γὰρ πολὺ τό τε ὑγρὸν καὶ τὸ σωματῶδες ἀναφέρεται.
ἱστάμενον μὲν οὖν βαρύνει καὶ ποιεῖ νυστάζειν· ὅταν
δὲ ῥέψῃ κάτω καὶ ἀντιστρέψαν ἀπώσῃ τὸ θερμόν, τότε γίγνεται
ὁ ὕπνος καὶ τὸ ζῷον καθεύδει. σημεῖον δὲ τούτων καὶ
τὰ ὑπνωτικά· πάντα γὰρ καρηβαρίαν ποιεῖ, καὶ τὰ ποτὰ
30 καὶ τὰ βρωτά, μήκων, μανδραγόρας, οἶνος, αἶραι. καὶ
καταφερόμενοι καὶ νυστάζοντες τοῦτο δοκοῦσι πάσχειν, καὶ
ἀδυνατοῦσιν αἴρειν τὴν κεφαλὴν καὶ τὰ βλέφαρα. καὶ μετὰ
τὰ σιτία μάλιστα τοιοῦτος ὁ ὕπνος· πολλὴ γὰρ ἡ ἀπὸ τῶν
σιτίων ἀναθυμίασις. ἔτι δ' ἐκ κόπων ἐνίων· ὁ μὲν γὰρ κόπος
35 συντηκτικόν, τὸ δὲ σύντηγμα γίγνεται ὥσπερ τροφὴ ἄπεπτος,
1We have treated of all this when discussing the subject of nutrition, but must here recapitulate what was there said, in order that we may obtain a scientific view of the beginnings of the process, and come to know what exactly happens to the primary organ of sense-perception to account for the occurrence of waking and sleep. For sleep, as has been shown, is not any given impotence of the perceptive faculty; 10for unconsciousness, a certain form of asphyxia, and swooning, all produce such impotence. Moreover it is an established fact that some persons in a profound trance have still had the imaginative faculty in play. This last point, indeed, gives rise to a difficulty; for if it is conceivable that one who had swooned should in this state fall asleep, the phantasm also which then presented itself to his mind might be regarded as a dream. 15Persons, too, who have fallen into a deep trance, and have come to be regarded as dead, say many things while in this condition. The same view, however, is to be taken of all these cases, [i.e. that they are not cases of sleeping or dreaming].
As we observed above, sleep is not co-extensive with any and every impotence of the perceptive faculty, but this affection is one which arises from the evaporation attendant upon the process of nutrition. 20The matter evaporated must be driven onwards to a certain point, then turn back, and change its current to and fro, like a tide-race in a narrow strait. Now, in every animal the hot naturally tends to move [and carry other things] upwards, but when it has reached the parts above [becoming cool], it turns back again, and moves downwards in a mass. This explains why fits of drowsiness are especially apt to come on after meals; 25for the matter, both the liquid and the corporeal, which is borne upwards in a mass, is then of considerable quantity. When, therefore, this comes to a stand it weighs a person down and causes him to nod, but when it has actually sunk downwards, and by its return has repulsed the hot, sleep comes on, and the animal so affected is presently asleep. A confirmation of this appears from considering the things which induce sleep; they all, whether potable or edible, 30for instance poppy, mandragora, wine, darnel, produce a heaviness in the head; and persons borne down [by sleepiness] and nodding [drowsily] all seem affected in this way, i.e. they are unable to lift up the head or the eye-lids. 35And it is after meals especially that sleep comes on like this, for the evaporation from the foods eaten is then copious.
As we observed above, sleep is not co-extensive with any and every impotence of the perceptive faculty, but this affection is one which arises from the evaporation attendant upon the process of nutrition. 20The matter evaporated must be driven onwards to a certain point, then turn back, and change its current to and fro, like a tide-race in a narrow strait. Now, in every animal the hot naturally tends to move [and carry other things] upwards, but when it has reached the parts above [becoming cool], it turns back again, and moves downwards in a mass. This explains why fits of drowsiness are especially apt to come on after meals; 25for the matter, both the liquid and the corporeal, which is borne upwards in a mass, is then of considerable quantity. When, therefore, this comes to a stand it weighs a person down and causes him to nod, but when it has actually sunk downwards, and by its return has repulsed the hot, sleep comes on, and the animal so affected is presently asleep. A confirmation of this appears from considering the things which induce sleep; they all, whether potable or edible, 30for instance poppy, mandragora, wine, darnel, produce a heaviness in the head; and persons borne down [by sleepiness] and nodding [drowsily] all seem affected in this way, i.e. they are unable to lift up the head or the eye-lids. 35And it is after meals especially that sleep comes on like this, for the evaporation from the foods eaten is then copious.
457a
1 ἂν μὴ ψυχρὸν ᾖ. καὶ νόσοι δέ τινες τὸ αὐτὸ τοῦτο ποιοῦσιν,
ὅσαι ἀπὸ περιττώματος ὑγροῦ καὶ θερμοῦ, οἷον συμβαίνει
τοῖς πυρέττουσι καὶ ἐν τοῖς ληθάργοις. ἔτι δ' ἡ πρώτη
ἡλικία· τὰ γὰρ παιδία καθεύδει σφόδρα διὰ τὸ τὴν
5 τροφὴν ἄνω φέρεσθαι πᾶσαν. σημεῖον δὲ τὸ ὑπερβάλλειν
τὸ μέγεθος τῶν ἄνω πρὸς τὰ κάτω κατὰ τὴν πρώτην ἡλικίαν,
διὰ τὸ ἐπὶ ταῦτα γίγνεσθαι τὴν αὔξησιν. διὰ ταύτην
δὲ τὴν αἰτίαν καὶ ἐπιληπτικὰ γίγνεται· ὅμοιον γὰρ ὁ ὕπνος
ἐπιλήψει, καὶ ἔστιν τρόπον τινὰ ὁ ὕπνος ἐπίληψις. διὸ καὶ
10 συμβαίνει τισὶν ἡ ἀρχὴ τούτου τοῦ πάθους καθεύδουσιν,
καὶ καθεύδοντες μὲν ἁλίσκονται, ἐγρηγορότες δ' οὔ· ὅταν
γὰρ πολὺ φέρηται τὸ πνεῦμα ἄνω, καταβαῖνον πάλιν τὰς
φλέβας ὀγκοῖ, καὶ συνθλίβει τὸν πόρον δι' οὗ ἡ ἀναπνοὴ
γίγνεται. διὸ τοῖς παιδίοις οὐ συμφέρουσιν οἱ οἶνοι, οὐδὲ ταῖς
15 τίτθαις (διαφέρει γὰρ ἴσως οὐδὲν αὐτὰ πίνειν ἢ τὰς τίτθας),
ἀλλὰ δεῖ πίνειν ὑδαρῆ καὶ ὀλίγον· πνευματῶδες γὰρ ὁ οἶνος
καὶ τούτου μᾶλλον ὁ μέλας. οὕτω δὲ τὰ ἄνω πλήρη
τροφῆς τοῖς παιδίοις, ὥστε πέντε μηνῶν οὐδὲ στρέφουσι
τὸν αὐχένα· ὥσπερ γὰρ τοῖς σφόδρα μεθύουσιν, ὑγρότης
20 ἀναφέρεται πολλή. εὔλογον δὲ τοῦτ' εἶναι τὸ πάθος αἴτιον
καὶ τοῦ ἠρεμεῖν ἐν ταῖς μήτραις τὰ ἔμβρυα τὸ πρῶτον. καὶ
τὸ ὅλον δὲ φίλυπνοι οἱ ἀδηλόφλεβοι καὶ οἱ νανώδεις καὶ
οἱ μεγαλοκέφαλοι· τῶν μὲν γὰρ αἱ φλέβες στεναί, ὥστ' οὐ
ῥᾴδιον διαρρεῖν κατιὸν τὸ ὑγρόν, τοῖς δὲ νανώδεσι καὶ μεγαλοκεφάλοις
25 ἡ ἄνω ὁρμὴ πολλὴ καὶ ἀναθυμίασις. οἱ δὲ
φλεβώδεις οὐχ ὑπνωτικοὶ δι' εὔροιαν τῶν πόρων, ἂν μή τι
ἄλλο πάθος ἔχωσιν ὑπεναντίον. οὐδ' οἱ μελαγχολικοί· κατέψυκται
γὰρ ὁ εἴσω τόπος, ὥστ' οὐ γίγνεται πλῆθος αὐτοῖς
ἀναθυμιάσεως. διὰ τοῦτο γὰρ καὶ βρωτικοί, σκληφροὶ ὄντες·
30 ὥσπερ γὰρ οὐδὲν ἀπολελαυκότα διάκειται τὰ σώματα αὐτοῖς.
ἡ δὲ μέλαινα χολὴ φύσει ψυχρὰ οὖσα καὶ τὸν
θρεπτικὸν τόπον ψυχρὸν ποιεῖ καὶ τὰ ἄλλα μόρια, ὅπου ἂν
ὑπάρχῃ δυνάμει τὸ τοιοῦτον περίττωμα. ὥστε φανερὸν ἐκ
1It also follows certain forms of fatigue; for fatigue operates as a solvent, and the dissolved matter acts, if not cold, like food prior to digestion. Moreover, some kinds of illness have this same effect; those arising from moist and hot secretions, as happens with fever-patients and in cases of lethargy. Extreme youth also has this effect; infants, for example, sleep a great deal, 5because of the food being all borne upwards-a mark whereof appears in the disproportionately large size of the upper parts compared with the lower during infancy, which is due to the fact that growth predominates in the direction of the former. Hence also they are subject to epileptic seizures; for sleep is like epilepsy, and, in a sense, actually is a seizure of this sort. Accordingly, 10the beginning of this malady takes place with many during sleep, and their subsequent habitual seizures occur in sleep, not in waking hours. For when the spirit [evaporation] moves upwards in a volume, on its return downwards it distends the veins, and forcibly compresses the passage through which respiration is effected. This explains why wines are not good for infants or for wet nurses (15for it makes no difference, doubtless, whether the infants themselves, or their nurses, drink them), but such persons should drink them [if at all] diluted with water and in small quantity. For wine is spirituous, and of all wines the dark more so than any other. The upper parts, in infants, are so filled with nutriment that within five months after birth they do not even turn the neck [sc. to raise thehead]; for in them, as in persons deeply intoxicated, 20there is ever a large quantity of moisture ascending. It is reasonable, too, to think that this affection is the cause of the embryo's remaining at rest in the womb at first. Also, as a general rule, persons whose veins are inconspicuous, as well as those who are dwarf-like, or have abnormally large heads, are addicted to sleep. For in the former the veins are narrow, so that it is not easy for the moisture to flow down through them; while in the case of dwarfs and those whose heads are abnormally large, 25the impetus of the evaporation upwards is excessive. Those [on the contrary] whose veins are large are, thanks to the easy flow through the veins, not addicted to sleep, unless, indeed, they labour under some other affection which counteracts [this easy flow]. Nor are the 'atrabilious' addicted to sleep, for in them the inward region is cooled so that the quantity of evaporation in their case is not great. For this reason they have large appetites, though spare and lean; 30for their bodily condition is as if they derived no benefit from what they eat.
457b
1 τῶν εἰρημένων ὅτι ὁ ὕπνος ἐστὶ σύνοδός τις τοῦ θερμοῦ εἴσω
καὶ ἀντιπερίστασις φυσικὴ διὰ τὴν εἰρημένην αἰτίαν· διὸ
πολλὴ ἡ κίνησις τοῦ ὑπνοῦντος. ὅθεν δ' ἐκλείπει, καταψύχεται
καὶ διὰ ψῦξιν καταπίπτει τὰ βλέφαρα, καὶ τὰ μὲν
5 ἄνω κατέψυκται καὶ τὰ ἔξω, τὰ δ' ἔντος καὶ τὰ κάτω
θερμά, οἷον τὰ περὶ τοὺς πόδας καὶ τὰ εἴσω. καίτοι τοῦτό τις
ἀπορήσειεν ἄν, ὅτι μετὰ τὰ σιτία ἰσχυρότατος ὁ ὕπνος γίγνεται,
καὶ ἔστιν ὑπνωτικὰ οἶνος καὶ ἄλλα θερμότητα ἔχοντα
τοιαῦτα, ἔστι δ' οὐκ εὔλογον τὸν μὲν ὕπνον εἶναι κατάψυξιν,
10 τὰ δ' αἴτια τοῦ καθεύδειν θερμά. πότερον οὖν τοῦτο
συμβαίνει ὅτι ὥσπερ ἡ κοιλία κενὴ μὲν οὖσα θερμή ἐστιν,
ἡ δὲ πλήρωσις αὐτὴν καταψύχει διὰ τὴν κίνησιν, οὕτω καὶ
οἱ ἐν τῇ κεφαλῇ πόροι καὶ τόποι καταψύχονται ἀναφερομένης
τῆς ἀναθυμιάσεως; ἢ ὥσπερ τοῖς προσχεομένοις τὸ
15 θερμὸν ἐξαίφνης φρίκη γίγνεται, κἀκεῖ ἀνιόντος τοῦ θερμοῦ
ἀθροιζόμενον τὸ ψυχρὸν καταψύχει, καὶ τὸ κατὰ φύσιν
θερμὸν ποιεῖ ἐξαδυνατεῖν καὶ ὑποχωρεῖν; ἔτι δὲ πολλῆς
ἐμπιπτούσης τροφῆς, ἣν ἀνάγει τὸ θερμόν, ὥσπερ τὸ πῦρ
ἐπιτιθεμένων τῶν ξύλων, καταψύχεται, ἕως ἂν καταπεφθῇ.
20 γίγνεται γὰρ ὁ ὕπνος, ὥσπερ εἴρηται, τοῦ σωματώδους ἀναφερομένου
ὑπὸ τοῦ θερμοῦ διὰ τῶν φλεβῶν πρὸς τὴν κεφαλήν·
ὅταν δὲ μηκέτι δύνηται, ἀλλὰ τῷ πλήθει ὑπερβάλλῃ
τὸ ἀναχθέν, πάλιν ἀνταπωθεῖται καὶ κάτω ῥεῖ (διὸ καὶ
πίπτουσί γε ὑποσπωμένου τοῦ θερμοῦ τοῦ ἀνάγοντος οἱ ἄνθρωποι·
25 μόνον γὰρ ὀρθὸν τῶν ζῴων), καὶ ἐπιπεσὸν μὲν ἔκνοιαν
ποιεῖ, ὕστερον δὲ φαντασίαν. ἢ αἱ μὲν νῦν λεγόμεναι λύσεις
ἐνδεχόμεναι μέν εἰσι τοῦ γίγνεσθαι τὴν κατάψυξιν, οὐ
μὴν ἀλλὰ κύριός γ' ἐστὶν ὁ τόπος ὁ περὶ τὸν ἐγκέφαλον,
ὥσπερ ἐν ἄλλοις εἴρηται. πάντων δ' ἐστὶ τῶν ἐν τῷ σώματι
30 ψυχρότατον ὁ ἐγκέφαλος, τοῖς δὲ μὴ ἔχουσι τὸ ἀνάλογον
τούτῳ μόριον. ὥσπερ οὖν τὸ ἀπατμίζον ὑγρὸν ὑπὸ τῆς τοῦ
ἡλίου θερμότητος, ὅταν ἔλθῃ εἰς τὸν ἄνω τόπον, διὰ τὴν
ψυχρότητα αὐτοῦ καταψύχεται καὶ συστὰν καταφέρεται
1The dark bile, too, being itself naturally cold, cools also the nutrient tract, and the other parts wheresoever such secretion is potentially present i.e. tends to be formed .
Hence it is plain from what has been said that sleep is a sort of concentration, or natural recoil, of the hot matter inwards [towards its centre], due to the cause above mentioned. Hence restless movement is a marked feature in the case of a person when drowsy. But where it [the heat in the upper and outer parts] begins to fail, he grows cool, and owing to this cooling process his eye-lids droop. Accordingly [in sleep] 5the upper and outward parts are cool, but the inward and lower, i.e. the parts at the feet and in the interior of the body, are hot.
Yet one might found a difficulty on the facts that sleep is most oppressive in its onset after meals, and that wine, and other such things, though they possess heating properties, are productive of sleep, for it is not probable that sleep should be a process of cooling 10while the things that cause sleeping are themselves hot. Is the explanation of this, then, to be found in the fact that, as the stomach when empty is hot, while replenishment cools it by the movement it occasions, so the passages and tracts in the head are cooled as the 'evaporation' ascends thither? Or, 15as those who have hot water poured on them feel a sudden shiver of cold, just so in the case before us, may it be that, when the hot substance ascends, the cold rallying to meet it cools [the aforesaid parts] deprives their native heat of all its power, and compels it to retire? Moreover, when much food is taken, which [i.e. the nutrient evaporation from which] the hot substance carries upwards, this latter, like a fire when fresh logs are laid upon it, is itself cooled, until the food has been digested.
For, as has been observed elsewhere, 20sleep comes on when the corporeal element [in the 'evaporation'] conveyed upwards by the hot, along the veins, to the head. But when that which has been thus carried up can no longer ascend, but is too great in quantity [to do so], it forces the hot back again and flows downwards. Hence it is that men sink down [as they do in sleep] when the heat which tends to keep them erect (25man alone, among animals, being naturally erect) is withdrawn; and this, when it befalls them, causes unconsciousness, and afterwards phantasy.
Or are the solutions thus proposed barely conceivable accounts of the refrigeration which takes place, while, as a matter of fact, the region of the brain is, as stated elsewhere, the main determinant of the matter? 30For the brain, or in creatures without a brain that which corresponds to it, is of all parts of the body the coolest.
Hence it is plain from what has been said that sleep is a sort of concentration, or natural recoil, of the hot matter inwards [towards its centre], due to the cause above mentioned. Hence restless movement is a marked feature in the case of a person when drowsy. But where it [the heat in the upper and outer parts] begins to fail, he grows cool, and owing to this cooling process his eye-lids droop. Accordingly [in sleep] 5the upper and outward parts are cool, but the inward and lower, i.e. the parts at the feet and in the interior of the body, are hot.
Yet one might found a difficulty on the facts that sleep is most oppressive in its onset after meals, and that wine, and other such things, though they possess heating properties, are productive of sleep, for it is not probable that sleep should be a process of cooling 10while the things that cause sleeping are themselves hot. Is the explanation of this, then, to be found in the fact that, as the stomach when empty is hot, while replenishment cools it by the movement it occasions, so the passages and tracts in the head are cooled as the 'evaporation' ascends thither? Or, 15as those who have hot water poured on them feel a sudden shiver of cold, just so in the case before us, may it be that, when the hot substance ascends, the cold rallying to meet it cools [the aforesaid parts] deprives their native heat of all its power, and compels it to retire? Moreover, when much food is taken, which [i.e. the nutrient evaporation from which] the hot substance carries upwards, this latter, like a fire when fresh logs are laid upon it, is itself cooled, until the food has been digested.
For, as has been observed elsewhere, 20sleep comes on when the corporeal element [in the 'evaporation'] conveyed upwards by the hot, along the veins, to the head. But when that which has been thus carried up can no longer ascend, but is too great in quantity [to do so], it forces the hot back again and flows downwards. Hence it is that men sink down [as they do in sleep] when the heat which tends to keep them erect (25man alone, among animals, being naturally erect) is withdrawn; and this, when it befalls them, causes unconsciousness, and afterwards phantasy.
Or are the solutions thus proposed barely conceivable accounts of the refrigeration which takes place, while, as a matter of fact, the region of the brain is, as stated elsewhere, the main determinant of the matter? 30For the brain, or in creatures without a brain that which corresponds to it, is of all parts of the body the coolest.
458a
1 γενόμενον πάλιν ὕδωρ, οὕτως ἐν τῇ ἀναφορᾷ τοῦ θερμοῦ τῇ
πρὸς τὸν ἐγκέφαλον ἡ μὲν περιττωματικὴ ἀναθυμίασις εἰς
φλέγμα συνίσταται (διὸ καὶ οἱ κατάρροι φαίνονται γιγνόμενοι
ἐκ τῆς κεφαλῆς), ἡ δὲ τρόφιμος καὶ μὴ νοσώδης
5 καταφέρεται συνισταμένη καὶ καταψύχει τὸ θερμόν. πρὸς
δὲ τὸ καταψύχεσθαι καὶ μὴ δέχεσθαι ῥᾳδίως τὴν ἀναθυμίασιν
συμβάλλεται καὶ ἡ λεπτότης καὶ [ἡ] στενότης τῶν
περὶ τὸν ἐγκέφαλον φλεβῶν. τῆς μὲν οὖν καταψύξεως τοῦτ'
ἐστὶν αἴτιον, καίπερ τῆς ἀναθυμιάσεως ὑπερβαλλούσης τῇ
10 θερμότητι. ἐγείρεται δ' ὅταν πεφθῇ καὶ κρατήσῃ ἡ συνεωσμένη
θερμότης ἐν ὀλίγῳ πολλὴ ἐκ τοῦ περιεστῶτος, καὶ
διακριθῇ τό τε σωματωδέστερον αἷμα καὶ τὸ καθαρώτερον.
ἔστι δὲ λεπτότατον μὲν αἷμα καὶ καθαρώτατον τὸ ἐν τῇ κεφαλῇ,
παχύτατον δὲ καὶ θολερώτατον τὸ ἐν τοῖς κάτω
15 μέρεσιν. παντὸς δὲ τοῦ αἵματος ἀρχή, ὥσπερ εἴρηται καὶ
ἐνταῦθα καὶ ἐν ἄλλοις, ἡ καρδία. τῶν δ' ἐν τῇ καρδίᾳ
ἑκατέρας τῆς θαλάμης κοινὴ ἡ μέση· ἐκείνων δ' ἑκατέρα
δέχεται ἐξ ἑκατέρας τῆς φλεβός, τῆς τε μεγάλης καλουμένης
καὶ τῆς ἀορτῆς· ἐν δὲ τῇ μέσῃ γίγνεται ἡ διάκρισις.
20 ἀλλὰ τὸ μὲν διορίζειν περὶ τούτων ἑτέρων ἐστὶ λόγων οἰκειότερον·
διὰ δὲ τὸ γίγνεσθαι ἀδιακριτώτερον τὸ αἷμα μετὰ τὴν
τῆς τροφῆς προσφορὰν ὕπνος γίγνεται, ἕως ἂν διακριθῇ
τοῦ αἵματος τὸ μὲν καθαρώτερον εἰς τὰ ἄνω, τὸ δὲ θολερώτερον
εἰς τὰ κάτω· ὅταν δὲ τοῦτο συμβῇ, ἐγείρονται ἀπολυθέντα
25 τοῦ ἐκ τῆς τροφῆς βάρους. τί μὲν οὖν τὸ αἴτιον τοῦ
καθεύδειν εἴρηται, ὅτι ἡ [ὑπὸ] τοῦ σωματώδους τοῦ ἀναφερομένου
ὑπὸ τοῦ συμφύτου θερμοῦ ἀντιπερίστασις ἀθρόως ἐπὶ
τὸ πρῶτον αἰσθητήριον· καὶ τί ἐστιν ὁ ὕπνος, ὅτι τοῦ πρώτου
αἰσθητηρίου κατάληψις πρὸς τὸ μὴ δύνασθαι ἐνεργεῖν, ἐξ
30 ἀνάγκης μὲν γινόμενος (οὐ γὰρ ἐνδέχεται ζῷον εἶναι μὴ
συμβαινόντων τῶν ἀπεργαζομένων αὐτό), ἕνεκα δὲ σωτηρίας·
σῴζει γὰρ ἡ ἀνάπαυσις.
1Therefore, as moisture turned into vapour by the sun's heat is, when it has ascended to the upper regions, cooled by the coldness of the latter, and becoming condensed, is carried downwards, and turned into water once more; just so the excrementitious evaporation, when carried up by the heat to the region of the brain, is condensed into a 'phlegm' (which explains why catarrhs are seen to proceed from the head); while that evaporation which is nutrient and not unwholesome, 5becoming condensed, descends and cools the hot. The tenuity or narrowness of the veins about the brain itself contributes to its being kept cool, and to its not readily admitting the evaporation. This, then, is a sufficient explanation of the cooling which takes place, despite the fact that the evaporation is exceedingly hot.
A person awakes from sleep when digestion is completed: when the heat, which had been previously forced together in large quantity within a small compass from out the surrounding part, 10has once more prevailed, and when a separation has been effected between the more corporeal and the purer blood. The finest and purest blood is that contained in the head, while the thickest and most turbid is that in the lower parts. 15The source of all the blood is, as has been stated both here and elsewhere, the heart. Now of the chambers in the heart the central communicates with each of the two others. Each of the latter again acts as receiver from each, respectively, of the two vessels, called the 'great' and the 'aorta'. It is in the central chamber that the [above-mentioned] separation takes place. 20To go into these matters in detail would, however, be more properly the business of a different treatise from the present. Owing to the fact that the blood formed after the assimilation of food is especially in need of separation, sleep [then especially] occurs [and lasts] until the purest part of this blood has been separated off into the upper parts of the body, and the most turbid into the lower parts. When this has taken place animals awake from sleep, being 25released from the heaviness consequent on taking food. We have now stated the cause of sleeping, viz. that it consists in the recoil by the corporeal element, upborne by the connatural heat, in a mass upon the primary sense-organ; we have also stated what sleep is, having shown that it is a seizure of the primary sense-organ, rendering it unable to actualize its powers; 30arising of necessity (for it is impossible for an animal to exist if the conditions which render it an animal be not fulfilled), i.e. for the sake of its conservation; since remission of movement tends to the conservation of animals.
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A person awakes from sleep when digestion is completed: when the heat, which had been previously forced together in large quantity within a small compass from out the surrounding part, 10has once more prevailed, and when a separation has been effected between the more corporeal and the purer blood. The finest and purest blood is that contained in the head, while the thickest and most turbid is that in the lower parts. 15The source of all the blood is, as has been stated both here and elsewhere, the heart. Now of the chambers in the heart the central communicates with each of the two others. Each of the latter again acts as receiver from each, respectively, of the two vessels, called the 'great' and the 'aorta'. It is in the central chamber that the [above-mentioned] separation takes place. 20To go into these matters in detail would, however, be more properly the business of a different treatise from the present. Owing to the fact that the blood formed after the assimilation of food is especially in need of separation, sleep [then especially] occurs [and lasts] until the purest part of this blood has been separated off into the upper parts of the body, and the most turbid into the lower parts. When this has taken place animals awake from sleep, being 25released from the heaviness consequent on taking food. We have now stated the cause of sleeping, viz. that it consists in the recoil by the corporeal element, upborne by the connatural heat, in a mass upon the primary sense-organ; we have also stated what sleep is, having shown that it is a seizure of the primary sense-organ, rendering it unable to actualize its powers; 30arising of necessity (for it is impossible for an animal to exist if the conditions which render it an animal be not fulfilled), i.e. for the sake of its conservation; since remission of movement tends to the conservation of animals.
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