Marquis De iMplace. 195 



which he never deviated ; for the unchangeable purpose of his 

 mind has always been the principal feature of his genius. He 

 already trenched upon the known limits of mathematical ana- 

 lysis ; — he was versed in the most ingenious and powerful parts 

 of this science ; and there was none more capable than he of 

 extending its domains. He had solved a leading question in 

 theoretical astronomy. He formed the project of consecrating 

 his efforts to this sublime science ; — he was destined to perfect 

 it, and was able to embrace it in all its extent. He thought 

 deeply upon his glorious purpose ; and he spent his whole life 

 in accomplishing it, with a perseverance of which the history 

 of the sciences presents perhaps no other example. 



The immensity of the subject flattered the just pride of his 

 genius. He undertook to compose the Almagest of his age. 

 This memorial he has left us under the name of the Mecanique 

 Celeste ; and his immortal work surpasses that of Ptolemy 

 as much as the modern analysis surpasses the Elements of Eu- 

 clid. 



Time, which is the only just dispenser of literary glory, and 

 which sinks into oblivion contemporary mediocrity, perpetu- 

 ates also the remembrance of great works. They alone con- 

 vey to posterity the character of each succeeding age. The 

 name of Laplace will thus live for ever ; — but, I hasten to add, 

 that enlightened and impartial history will never separate his 

 memory from that of the other successors of Newton. It will 

 conjoin the illustrious names of D'Alembert, Clairaut, Euler, 

 Lagrange, and Laplace. I confine myself at present to the 

 mere mention of the great geometers whom the sciences have 

 lost, and whose researches had for their common object the 

 perfection of physical astronomy. 



In order to give a just idea of their works, it would be ne- 

 cessary to compare them ; but the limits of a discourse like this 

 oblige me to reserve a part of this discussion for the collection 

 of our Memoirs. 



Next to Euler, Lagrange contributed most to the founda- 

 tion of mathematical analysis. In the writings of these two 

 great geometers it has become a distinct science, the only one 

 of the mathematical theories of which we can say that it is 

 completely and rigorously demonstrated. Among all these 



