THE PATH OF EVOLUTION 



into which he was drawn by Hooke, by Leibnitz 

 and by others with reference to the originality and 

 priority of his discoveries, which in 1693 so injured 

 his health that for many months afterwards his 

 reason was affected. Rest and quiet restored him ; 

 but in his works on optics that appeared in 1704, 

 and in later works on science, he always stated that 

 they were titles of ancient works that he had com- 

 posed long before, and in which, though they needed 

 revision and extension, of which he felt the necessity, 

 in order that they might be nearer perfect, yet he 

 could not bring himself to undertake the work. The 

 appointment to the Directorship of the Mint in 1699 

 gave him a competent livelihood. In 1703 he be- 

 came President of the Royal Society of London, 

 which he retained for twenty-five years, until his 

 death. In 1705 Queen Anne knighted him. The 

 disputes between Leibnitz and Newton concerning 

 the differential calculus continued with increasing 

 acerbity until the death of the former in 1716. It 

 must be said that each was unjust to the other, and 

 Newton was even more so than his opponent. 



Newton was a believer in the science of Alchemy. 

 He pursued his experiments in the search of the 

 Philosopher's Stone until late in life. The famil- 

 iarity with chemical reactions thus obtained was of 

 service to him when he was placed in charge of the 



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