THE SCIENCE OF HAPPINESS 



There is a third condition, however, which thrusts 

 itself upon the attention ; an intermediate state of mental 

 activity which is not strictly speaking conscious, though 

 recalled and reproduced by waking consciousness. 

 This intermediate period is called the dream-state. 

 It is open to question whether the dream is a normal 

 phenomenon, but it is so slightly abnormal at most, 

 and so universal an experience that it cannot be over- 

 looked in a general discussion. 



What then is a dream ? 



To the best of our knowledge, a dream is the result 

 of an isolated or partial activity of the brain, at a time 

 when the general level of cerebral energising is below 

 the level of consciousness. During waking hours, one 

 or another set of brain cells is always most active, but 

 these cells are always co-ordinated with other sets 

 that are also active, the result being that consciousness 

 is never a single train of thought, but a series of rela- 

 tively vivid ideas placed in a setting of less vivid ideas. 

 The subsidiary ideas furnish the mind its perspective 

 or vista its "third dimension" and they are a con- 

 stant and necessary corrective in enabling the organ- 

 ism to judge rationally of its true relation to its environ- 

 ment. The absence, or very great restriction, of such 

 mental perspective, due to the general inactivity of the 

 brain, is the essential difference between the dream 

 and waking consciousness. It is for this reason that 

 the ideas of the dream have such seeming thraldom 

 over the mind. The most grotesque creature of the 

 imagination, appearing during sleep, and hence without 

 a vista of corrective ideas, imposes itself on the mind 



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