Thus, Dr.Heidenhain tells us that the threshold or liminal value of stimulation is lowered just as in ordinary sleep sense-activity as a whole is lowered.
According to Professor Weinhold, the hypnotic condition begins in a gradual loss of taste, touch, and the sense of temperature; then sight is gradually impaired, while hearing remains throughout the least interfered with.[102] In this way, the mind of the patient is largely cut off from the external world, as in sleep, and the power of orientation is lost.

Moreover, there are all the conditions present, both positive and negative, for the hallucinatory transformation of mental images into percepts just as in natural sleep.

Thus, the higher centres connected with the operations of reflection and reasoning are thrown _hors de combat_ or, as Dr.Heidenhain has it, "inhibited." The condition of hypnotism is marked off from that of natural sleep, first of all, by the fact that the accompanying hallucinations are wholly due to external suggestion (including the effects of bodily posture).

Dreams may, as we have seen, be very faintly modified by external influences, but during sleep there is nothing answering to the perfect control which the operator exercises over the hypnotized subject.

The largest quantity of our "dream-stuff" comes, as we have seen, from within and not from without the organism.