An Introduction to a Biology 



not to have been cut out, and whether some that 

 died and has long since disappeared ought not to 

 have survived and altered the shape of the tree. In 

 other words we should ask ourselves, are we working 

 in the right direction ? 



For my own part, I believe that at certain points 

 in the history of our attempts to interpret life wrong 

 signals were given and that as a consequence we are 

 at present working along the wrong lines. I am not 

 concerned at present with the nature of this false 

 step ; all I am concerned with now is to express my 

 belief that the satisfaction of the biologist with our 

 current scientific interpretation of life is the satisfac- 

 tion of the fool with the paradise which he has built. 



The cocksureness of the scientific biologist should 

 fsurely be the cause of the gravest misgivings. The 

 more certain a man is that he is right the more 

 probable is it that he is wrong ; because it means 

 that facts are as soft clay in his hands, and his cer- 

 tainty moulds them to his purpose. It is the diffident 

 investigator who tentatively offers us a hypothesis 

 which, in his modest view, brings some of the facts 

 into line, who should inspire us with confidence. It 

 is the theory which seems to fit the facts in places 

 but seems remote from them in others (as, for in- 

 stance, the theory of sex based on clinical, Mendelian 

 and cytological phenomena and upon the facts of 

 parasitic castration) and not the theory which 

 peremptorily brings all the facts into line, which 

 should seem to us to be likely to be true. 



If a man came to me to-morrow, full of con- 



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