THE ART OF SCIENTIFIC INVESTIGATION 



fleetingly and disappear again like the things we were about to 

 say but slipped away irretrievably before there was a break in 

 the conversation? According to the hypothesis just outlined the 

 more emotion associated with the idea the more likely it would 

 be to get through to the consciousness. On this reasoning one 

 would expect it to be helpful to have a strong desire for a solution 

 to the problem and also to cultivate a "taste" in scientific matters. 

 It would be interesting to know whether scientists who say they 

 never get intuitions are those who find no joy in new ideas or are 

 deficient in emotional sensitivity. 



The conception of the psychology of intuition outlined is in 

 accord with what is known about the conditions that are con- 

 ducive to their occurrence. It provides an explanation for the 

 importance of (a) freedom from other competing problems and 

 worries, and {b) the helpfulness of periods of relaxation in 

 allowing for the appearance of the intuition, for messages from 

 the subconscious may not be received if the conscious mind is 

 constantly occupied or too fatigued. There have been several 

 instances of famous generalisations coming to people when they 

 were ill in bed. The idea of natural selection in evolution came 

 to Wallace during a bout of malaria, and Einstein has reported 

 that his profound generalisation connecting space and time 

 occurred to him while he was sick in bed. Both Cannon and 

 Poincare report having got bright ideas when lying in bed unable 

 to sleep — the only good thing to be said for insomnia ! It is said 

 that James Brindley, the great engineer, when up against a 

 difficult problem, would go to bed for several days till it was 

 solved. Descartes is said to have made his discoveries while lying 

 in bed in the morning and Cajal refers to those placid hours after 

 awakening which Goethe and so many others considered pro- 

 pitious to discovery. Walter Scott wrote to a friend : 



" The half hour between waking and rising has all my life 

 proved propitious to any task which was exercising my invention. 

 ... It was always when I first opened my eyes that the desired 

 ideas thronged upon me." 



Baker finds lying in the bath the ideal time and suggests that 

 Archimedes hit upon his famous principle in the bath because of 

 the favourable conditions and not because he noticed the 

 buoyancy of his body in water. The favourable effects of the bed 



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