ii6 GREAT MEN OF SCIENCE 



Leibniz accepted an invitation to the court of Duke Johann 

 Friedrich, of Hanover, with whom he had already been in 

 correspondence for some time, and this ended his stay in 

 Paris. The return journey to Germany was made via 

 England and Holland. When in London, where he only 

 stayed a week, he inspected manuscripts of Newton, which 

 contained matter relating to the calculus of fluxions. This 

 was also before his first publication on this subject, and hence 

 it cannot be doubted that Leibniz did not work independ- 

 ently of Newton, who was the first to conceive the idea of 

 calculation with infinitely small quantities. But it is like- 

 wise clear that these ideas had gradually become known to 

 many both from Newton and from Leibniz's remarks, and 

 that nevertheless no one other than these two was able to 

 give them permanent form; and further, that Leibniz alone 

 gave them the final form which was so favourable for their 

 application. 



At the court of Hanover, Leibniz was first employed as 

 Librarian, and as writer of the history of the royal house; 

 but he was soon in request for higher matters of law and 

 state. Along with these activities, and many other interests, 

 he published during this period a further series of very im- 

 portant mathematical essays, relating to the further develop- 

 ment and application of the differential calculus. 



The last period of Leibniz's life brought him few satis- 

 factions. It is true that he was able to witness the beginning 

 of the rapid application and development of the differential 

 calculus; but during his lifetime his services in this respect 

 were not recognised. It appeared for a time, however, as if 

 he would receive the major portion of the credit, since in his 

 publication he did not refer to the assistance which he had 

 received, apart from Huygens, particularly in the circle of 

 the Royal Society, whereas Newton openly recognised^ that 



1 Principia, lib. 2, sectio 2, lemma 2, scolium (1686, two years after 

 Leibniz's first publication concerning the difierential calculus). 



