Aristotle on sleep and dreams 199
For when the body is awake, the soul is its servant: it is divided among many parts
of the body and is never on its own, but assigns a part of itself to each part of the
body: to hearing, sight, touch, walking, and to acts of the whole body; but the
mind is never on its own. However, when the body is at rest, the soul, being set
in motion and awake, administers its own household and of itself performs all the
acts of the body. For the body when asleep has no perception; but the soul, which
is awake, cognises all things: it sees what is visible, hears what is audible, walks,
touches, feels pain, ponders, though being only in a small space. All functions of
the body or of the soul are performed by the soul during sleep. Whoever, therefore,
knows how to interpret these acts correctly, knows a great part of wisdom. (On
Regimen 4. 86 )
He presents soul and body as two separate entities which co-operate in the
waking state but whose co-operation ends in sleep.^51 Aristotle, however,
views the soul as the principle of organisation of all bodily functions, the
formal apparatus which enables every organism to live and to realise its
various functions. It would be impossible for Aristotle to say – as the writer
ofOn Regimendoes – that in sleep the body is at rest but that the soul
works. Sleep is for Aristotle an affection ofthe complexof soul and body
due to the heating and cooling of food and preventing the animal from
perceiving actual sense movements.
It is obvious, therefore, that we cannot say that Aristotle isinfluencedhere
by the medical writer’s views on dreams. It would be more appropriate to
say that the non-specialised student of nature gives a theoretical explanation
or even a justification of the view held by the distinguished doctors; this
justification is given entirely in Aristotle’s own terminology and based on his
own presuppositions (the two principles mentioned above). This procedure
is completely in accordance with his general views on the relation between
natural science and medicine discussed above.
However, the incorporation of the medical view on the prognostic value
of dreams into his own theory of sleep and dreams does confront Aristotle
with a difficulty which he does not seem to address very successfully. For,
as we have seen above, inOn DreamsAristotle says that dreams are based
on the remnants of small sensitive movements which we receive in the
waking state but do not notice at the time, because they are overruled by
more powerful movements which claim all our attention. Yet during sleep,
when the input of stronger competing sensitive movements has stopped,
the remnants of these small movements come to the surface and present
themselves to us in the form of dreams. As I have already said, it is exactly
this mechanism to which Aristotle seems to refer inDiv. somn. 463 a 7 – 11.
(^51) On this conception see Cambiano ( 1980 ) 87 – 96.