NEWTON. 205 



"Prifidpia" and the cogency and clearness of the reasoning by which 

 it was supported, would, it might be supposed, have caused it to be 

 immediately received in all the schools of philosophy of Europe. It 

 is, however, rarely the case that great truths find immediate accept- 

 ance. It was not now the philosophy of Aristotle that stood in the 

 way. The system of Descartes had completely displaced that of 

 Aristotle, and held possession of the learned and of the popular mind. 

 The vortexes presented a perfectly intelligible point of view, and the 

 cause thus assigned for the planetary motion was of so obvious a cha- 

 racter that mathematical abstractions were less relied upon for the 

 support of the theory than an appeal to apparently conclusive experi- 

 ments. Newton's theory, on the other hand, presented ideas that 

 could not fail to offer great difficulties, to the less trained minds at 

 least : enormous masses of matter, so to speak, in empty space, and 

 as planets retained in their orbits by some invisible influence con- 

 necting them with the sun. Even those accustomed to the vigour of 

 mathematical reasoning would find in the establishing of the proofs 

 of the Newtonian system an additional difficulty in the circumstance 

 that a new kind of geometry, transcending the powers of the old methods, 

 had to be invented for these investigations. It has been said that 

 at the time the " Prindpia" appeared, there were not eight persons 

 who understood the reasonings of the work. Even Leibnitz, mis- 

 apprehending the principles of Newton's philosophy, regarded the idea 

 of gravitation as a revival of the "occult qualities" of an ancient sect 

 of philosophers, and he endeavoured to demonstrate astronomical truths 

 on very different principles. Huyghens. who might be supposed well 

 able to appreciate the new doctrine, could not admit that a mutual 

 attraction existed between the particles of matter, but perceived that 

 the law of attraction did subsist between the several planets. Bernou- 

 illi, one of the ablest mathematicians of the time, opposed the New- 

 tonian system altogether. Cassini, Maraldi, and others, continued to 

 adhere to most absurd methods of calculating cometary orbits after 

 the publication of the "Principta" Fontenelle, one of the most accom- 

 plished French savans of his time, continued to maintain the doctrines 

 of Descartes. 



The beginning of the eighteenth century, however, witnessed the 

 introduction of the Newtonian philosophy into the universities of 

 Great Britain, where the Cartesian theories perhaps lingered longest 

 Dr. Keill, the first person who publicly gave experimental lectures on 

 natural philosophy, taught the principles of Newton's Physics in this 

 way at Oxford as early as 1 704. His plan, we are told, was to lay down 

 very simple propositions, which he proved by experiments ; from these 

 propositions he deduced others, still confirming them by experiments. 

 But it was at the hands of the great Continental mathematicians of the 

 following century that the philosophy of the "Prindpia* received its 

 complete development. From the works of Laplace, Lagrange, Biot, 



