A. INTRODUCTION 

 LECTURE I 



DESCENT : THEORIES OF EVOLUTION, AND METHODS 

 OF INVESTIGATION 



Newton convinced his contemporaries that 

 natural laws rule the whole universe. Lyell 

 showed, by his principle of slow and gradual 

 evolution, that natural laws have reigned since 

 the beginning of time. To Darwin we owe the 

 almost universal acceptance of the theory of 

 descent. 



This doctrine is one of the most noted land- 

 marks in the advance of science. It teaches the 

 validity of natural laws of life in its broadest 

 sense, and crowns the philosophy, founded by 

 Newton and Lyell. 



Lamarck proposed the hypothesis of a com- 

 mon origin of all living beings and this ingenious 

 and thoroughly philosophical conception was 

 warmly welcomed by his partisans, but was not 

 widely accepted owing to lack of supporting evi- 

 dence. To Darwin was reserved the task of 



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