THE ART OF SCIENTIFIC INVESTIGATION 



critical age, as many great scientists have published their most 

 important work at that age. On the other hand, some individuals 

 continue to do first-rate research till they are past 70. Pavlov, 

 Sir Frederic Gowland Hopkins and Sir Joseph Barcroft are good 

 examples. 



The fact that a person has not made a significant contribution 

 by the time he is 40 does not necessarily mean he never will, 

 for such cases have occurred, though not often. With advancing 

 age most minds become less receptive to new ideas suggested by 

 others and probably also arising from their work or thinking. 

 William Harvey stated that no man over forty accepted the idea 

 of the circulation when he first advanced it. The reason why 

 many lose their productivity about middle age is often simply 

 due to their having taken on administrative responsibilities that 

 do not allow time for research. In other cases indolence develops 

 with middle age and security, and drive is lost. Contact with 

 young minds often helps to preserve freshness of outlook. What- 

 ever the reasons for the frequent falling off of productivity after 

 middle age, its occurrence shows that accumulation of know- 

 ledge and experience is not the main factor in successful research. 



W. Ostwald considered that the frequent decrease of product- 

 ivity with increasing age is due to too long familiarity with the 

 same subject. The way in which accumulated information 

 handicaps originality was discussed in the first chapter of this 

 book. For scientists past middle age who have lost originality, 

 Ostwald advocated a radical change of field of work. In his 

 own case he was evidently successful in refreshing his mind by 

 this means when he was over fifty years of age. 



The research scientist is fortunate in that in his work he can 

 find something to give meaning and satisfaction to life. For 

 those who seek peace of mind by sinking their personality in 

 something bigger than themselves, science can have a special 

 appeal, while the somewhat more material-minded can get 

 gratification from the knowledge that his achievements in 

 research have an immortality. Few callings can claim to have 

 as much influence on the welfare of mankind as scientific 

 research, especially in the medical and biological sciences. 

 Brailsford Robertson said : " The investigator is the pathfinder 

 and the pioneer of new civilisations."^* The human race has 



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