254: MYTH AND SCIENCE. 



normal images and hallucinations, and afterwards 

 into those of dreams, properly so called. 



If the hypnagogic phase actually affects the 

 cerebral cellules in connection with the various senses 

 of which they are the organs, the phases of sleep and 

 dreams, strictly so called, have more general con- 

 ditions. The idea, converted into an image presented 

 to the senses, may thus be said to have three stages : 

 that of the waking state, which depends as we have 

 said on the intensity and vividness with which it is 

 reproduced, aided by a momentary detachment from 

 the real environment ; secondly, the hypnagogic phase, 

 in which there is the physiological action of the 

 nervous centres, .which produce the image, though 

 still with the implicit consciousness of the waking 

 state ; and finally, the actual dream, in which this 

 implicit consciousness is almost always wanting, and 

 the psychical exercise of thought is completely trans- 

 formed into visions and figures which are believed to 

 be real. This in its turn depends upon the other two 

 causes, and on the physiological relaxation of the 

 body, which is to a great extent isolated, so that 

 the effectual impulses of external nature are greatly 

 attenuated. 



In the waking state, the whole body and all its 

 organs of relation and movement are in tension. 

 The cerebro-spinal axis virtually excites the whole 

 muscular and peripheral system in such a way that 

 relaxation or relative repose becomes impossible. 



