CHAPTER V. DREAMS.

Physiology of perception and of dreaming--Definition of the act of dreaming--Revery--Production of illusions and hallucinations by drugs and by disease--Effects of hasheesh--Effects of acute disease--Association of ideas--Memory of past sensations--Dreams produced by excitement of the different organs of sense--Persistence of dream-impressions after waking--Experience of M. Baillarger--Of Professor Jessen--Belief of savages in the reality of dreams--Sensory dreams--Intellectual dreams-- Repetition of dreams--Incoherence of dreams--Cause of the superior vividness of certain dreams--Duration of dreams-- Dreams excited by morbid states of the body--Prophetic dreams--Their causes--Clairvoyant dreams--Hallucinatory dreams--Sir Edmund Hornby’s experience--Hallucinations-- Case related by Dr. E. H. Clarke--Revelation through dreams--Revival of memory in dreams. 116