On Dreams   

affection of the faculty of perception in the simple sense. If it were

the latter it would be possible [when asleep] to hear and see in the

simple sense.

How then, and in what manner, it takes place, is what we have to

examine. Let us assume, what is indeed clear enough, that the

affection [of dreaming] pertains to sense-perception as surely as

sleep itself does. For sleep does not pertain to one organ in

animals and dreaming to another; both pertain to the same organ.

But since we have, in our work On the Soul, treated of presentation,

and the faculty of presentation is identical with that of

sense-perception, though the essential notion of a faculty of

presentation is different from that of a faculty of

sense-perception; and since presentation is the movement set up by a

sensory faculty when actually discharging its function, while a

dream appears to be a presentation (for a presentation which occurs in

sleep-whether simply or in some particular way-is what we call a

dream): it manifestly follows that dreaming is an activity of the

faculty of sense-perception, but belongs to this faculty qua

presentative.



2



We can best obtain a scientific view of the nature of the dream

and the manner in which it originates by regarding it in the light

of the circumstances attending sleep. The objects of

sense-perception corresponding to each sensory organ produce

sense-perception in us, and the affection due to their operation is

present in the organs of sense not only when the perceptions are

actualized, but even when they have departed.

What happens in these cases may be compared with what happens in the

case of projectiles moving in space. For in the case of these the

movement continues even when that which set up the movement is no