MEDICINE AND PHILOSOPHY IN CLASSICAL ANTIQUITY

Aristotle on melancholy 147

Sleep(which makes no mention ofpneumaand blood at all and which

otherwise shows a lack of physiological details too).

However, close analysis of the text ofOn Dreamsreveals a clear connec-

tion between both occurrences. At the start of the third chapter Aristotle

explains what causes dreams to appear: due to their weakness, sensory move-

ments are obscured by stronger movements during the day; yet by night,

when the individual senses are inactive, they flow to the central sensory

organ (the ‘principle of perception’ or the ‘authoritative sense-organ’ that is

situated in the heart) as a result of a flow of heat. These movements often still

resemble the object originally perceived, but equally often they take on dif-

ferent shapes due to resistance (for this reason no dreams occur after a meal).

Hence, just as in a liquid, if one disturbs it violently, sometimes no image appears,

and sometimes it appears but is entirely distorted, so that it seems quite different
from what it really is,although when the movement has ceased, the reflections are

clear and plain; so also in sleep, the images or residuary movements that arise from

the sense-impressions are altogether obscured owing to the aforesaid movement

when it is too great, and sometimes the images appear confused and monstrous,

and the dreams are morbid, as is the case with the melancholic, the feverish and

the intoxicated; for all these affections, being full of air, produce much movement

and confusion. In animals that have blood,as the blood becomes quiet and its purer

elements separate, the persistence of the sensory stimulus derived from each of the

sense organs makes the dreams healthy.

The analogy thus has to be considered to apply to the whole process: the

phrase ‘when the movement has ceased, the reflections are clear and plain’

( 17 ) corresponds to ‘as the blood becomes quiet and its purer elements

separate’ in line 25. It shows that the process does not stop at the confused

images in dreams: if the movement is preserved ()n= #), it will eventu-

ally reach the heart. It seems thatDiv. somn. 464 a 32 ff. refers in particular

to this ‘preservation’ of movements, for the ‘intensity’ of the melancholics

that is emphasised there is responsible for this preservation, and the ‘other

movement’ discussed here seems to refer to the ‘resistance’ (ekkrousis) men-

tioned inInsomn. 461 a 11. The advantage of this interpretation is that in the

later treatise (On Divination in Sleep) Aristotle explicitly refers to the earlier

one (On Dreams), using it to try to explain two facts and characteristics

of melancholics that at first sight seem difficult to square with each other.

It appears that melancholics can have both vague and clear dreams; and

which one of both affections manifests itself most strongly in a particu-

lar case apparently depends on the person’s physiological state at the time

(volume of air and heat, intensity of images), which in the case of unstable

people like melancholics must be considered a variable factor.