DAEWIN'S DEBT TO LYELL 87 



When did Darwin acknowledge his debt in 

 this way ? It was on Aug. 29th, 1844. In 1842 

 he had written the first brief account of his 

 theory of evolution— that sketch which will now 

 be for the first time in the hands of the public — 

 that sketch of which, thanks to your generosity, a 

 gift has been made to every guest whom you are 

 welcoming to Cambridge, a work which I for my 

 part look forward to reading with greater pleasure 

 and greater interest than any book I have ever 

 possessed. In 1844 Darwin had further 

 elaborated this sketch into a completed essay 

 which he felt, whatever happened, would contain 

 a sufficient account of his views ; and on July 5 

 he made his 'solemn and last request' to his 

 wife, begging her, in the event of his death, to 

 make arrangements for its publication. Only a 

 few weeks after this, the psychological moment 

 in his career, Darwin acknowledged his debt to 

 Lyell; and when we consider how intensely 

 Lyellian were the three lines of argument — two 

 based on geographical distribution, and one on 

 the relation between the most recent fossils and 

 the forms now living in a country — by which 

 Darwin was first convinced of the truth of 

 evolution, we cannot avoid the conclusion that 

 he was right in feeling the debt to be a very 

 heavy one. 



Although Darwin spoke of the three years at 

 Cambridge as * the most joyful in my happy life ', 

 neither he nor Lyell appear to have thought that 



