_Classical and Medieval Views of Dreams._--Side by side with the prevalent animistic view of dreams we find in antiquity and among the semi-civilized attempts at philosophical or physiological explanations of dreams. Democritus, from whom the Epicureans derived their theory, held the cause of them to be the simulacra or phantasms of corporeal objects which are constantly floating about the atmosphere and attack the soul in sleep--a view hardly distinguishable from animism. Aristotle, however, refers them to the impressions left by objects seen with the eyes of the body; he further remarks on the exaggeration of slight stimuli when they are incorporated into a dream; a small sound becomes a noise like thunder. Plato, too, connects dreaming with the normal waking operations of the mind; Pliny, on the other hand, admits this only for dreams which take place after meals, the remainder being supernatural. Cicero, however, takes the view that they are simply natural occurrences no more and no less than the mental operations and sensations of the waking state. The pathological side of dreams attracted the notice of physicians. Hippocrates was disposed to admit that some dreams might be divine, but held that others were premonitory of diseased states of the body. Galen took the same view in some of his speculations.
Symbolical interpretations are combined with pathological no less than animistic interpretations of dreams; they are also extremely common among the lower classes in Europe at the present day, but in this case no consistent explanation of their importance for the divination of future events is usually discoverable. Among the Greeks Plato in the _Timaeus_ (ch. xlvi, xlvii) explains dreams as prophetic visions received by the lower appetitive soul through the liver; their interpretation requires intelligence. The Stoics seem to have held that dreams may be a divine revelation and more than one volume on the interpretation of dreams has come down to us, the most important being perhaps the [Greek: Oneirokritika] of Daldianus Artemidorus. We find parallels to this in a Mussulman work by Gabdorrachaman, translated by Pierre Vattier under the name of _Onirocrite mussulman_, and in the numerous books on the interpretation of dreams which circulate at the present day. In Siam dream books are found (_Intern. Archiv für Anthr._ viii 150); one of the functions of the Australian medicine man is to decide how a dream is to be interpreted.