in the SeventeentJi Century. 3 



powers of one man or one generation, he left to posterity the 

 work of filling in the framework which he had designed. 

 Descartes, on the other hand, desired to leave as little as possible 

 for his successors to do ; his was a theory of the universe, worked 

 out as far as possible in every detail. It is, however, impossible 

 to derive such a theory inductively unless there are at hand 

 sufficient observational data on which to base the induction ; 

 and as such data were not available in the age of Descartes, 

 he was compelled to deduce phenomena from preconceived 

 principles and causes, after the fashion of the older philosophers. 

 To the inherent weakness of this method may be traced the 

 errors that at last brought his scheme to ruin. 



The contrast between the systems of Bacon and Descartes is 

 not unlike that between the Eoman republic and the empire of 

 Alexander. In the one case we have a career of aggrandizement 

 pursued with patience for centuries ; in the other a growth of 

 fungus-like rapidity, a speedy dissolution, and an immense 

 influence long exerted by the disunited fragments. The 

 grandeur of Descartes' plan, and the boldness of its execution, 

 stimulated scientific thought to a degree before unparalleled ; 

 and it was largely from its ruins that later philosophers 

 constructed those more valid theories which have endured to 

 our own time. 



Descartes regarded the world as an immense machine, 

 operating by the motion and pressure of matter. " Give me 

 matter and motion," he cried, " and I will construct the universe." 

 A peculiarity which distinguished his system from that which 

 afterwards sprang from its decay was the rejection of all forms 

 of action at a distance ; he assumed that force cannot be com- 

 municated except by actual pressure or impact. By this 

 assumption he was compelled to provide an explicit mechanism 

 in order to account for each of the known forces of nature a 

 task evidently much more difficult than that which lies before 

 those who are willing to admit action at a distance as an 

 ultimate property of matter. 



Since the sun interacts with the planets, in sending them 



B 2 



