Medicine and philosophy - Classical Homeopathy Online

176 Aristotle and his school(either perceptual or intellectual, and either ‘normal’ or extraordinary) insleep. But this question is not explicitly raised, and his relevant remarksare scattered, nuanced and complicated, so that an answer unfolds onlygradually through the continuous discussion in the three works; and it isnot free from apparent contradictions. In On Sleep and Waking, Aristotlebegins by defining sleep negatively as the inability of the sense faculty tobe activated (adunamia tou energein, 454 b 5, 458 a 29). Sleep is said tobe a ‘fetter and immobilisation’ (desmos kai akinēsia, 454 b 10) an ‘inactivity’(argia) or ‘incapacitation’ (adunamia) of the sensitive faculty (455 b3ff.). It is a state in which the vegetative part of the soul gains the upperhand (455 a 1–2), and it is caused by various physiological processes thatare connected with the digestion of food (such as heating, cooling, evaporationof food, and sifting of the blood). 19 There is no sensation in sleep,he says, because the central sense-organ, the kurion aisthētērion, which islocated in the heart, is affected by these processes and thus incapacitated,and as a result of this the peripheral sense-organs (eyes, ears, nose, etc.)cannot function either (455 a 13ff.). Whether these physiological processesalso affect the ability to think and the operations of the intellectual part ofthe soul, is a question which Aristotle does not address explicitly. Strictlyspeaking, since Aristotle’s supreme intellectual faculty, the nous, is said tobe incorporeal and not to require simultaneous perception in order to beactive, 20 there is, at least in principle, no reason why we should not be ableto think while being asleep. 21 There are a few hints to this in the text, forexample in Insomn. 459 a 6–8 and 462 a 29–30, which speak of an activity of‘judgement’ (doxa) and of the presence of ‘true thoughts’ (alētheis ennoiai)in sleep, but it remains vague (see below).Aristotle’s negative definition of sleep does not, however, imply a negativeevaluation of this ‘affection’ (pathos). Sleep is a good thing and serves apurpose, for it provides rest (anapausis) to the sense-organs, which wouldotherwise become overstretched, since they are unable to be active withoutinterruption (454 a 27, 455 b 18ff.). Here, again, one may note a differencecompared with thinking; for one of the differences between perception andthinking, according to Aristotle, is that perception cannot go on forever,indeed if we overstretch our sense-organs, we damage them; thinking, on19 For a discussion of Aristotle’s physiological explanation of sleep see Wiesner (1978).20 De an. 430 a 17–18, 22–3; Gen. an. 736 b 28–9; see also ch. 7 below.21 In De an. 429 a 7–8 Aristotle mentions the possibility that the intellect (nous) may be ‘overshadowed’(epikaluptesthai) by sleep, but it is unclear from this passage whether this is always the case in sleepor only in exceptional circumstances.