TRANSLATOR'S INTRODUCTION Ixv 



Planets and their satellites are kept revolving in 

 their orbits in constant periods by this obscure 

 centripetal force ; it does not explain how they are 

 found to be moving round and round in these 

 orbits, or how they acquired the tangential or 

 centrifugal force by which Newton represented 

 them as driven on. It was at this point where 

 Newton's Law of Attraction stopped, and it failed to 

 explain the revolutional and rotatory motions of 

 the solar system. And Newton in the last resort 

 could only explain them by the immediate inter- 

 position of God, who directly communicated these 

 motions to the full-formed Planets and their 

 attendants by impulses from without. In the 

 devout recognition of God's miraculous agency, not 

 only in creating the material of the solar system 

 but in setting its motions agoing, Newton's Natural 

 Philosophy came to a pause. So far as it went 

 Kant accepted it in its entirety, but he was stimu- 

 lated by the fertile idea of another English thinker 

 to go far beyond it. 



4. Kant and Thomas Wright of Durham. To 

 Thomas Wright of Durham undoubtedly belongs 

 the bold and original idea of transcending Newton 

 on his own lines, by carrying his conception of the 

 finite solar system into the infinite world of the 

 stars beyond it. Wright's speculations have extra- 

 ordinary originality and merit, although accom- 

 panied with considerable arbitrariness and fanciful 

 conjecture in detail. He was the first to pro- 



