X PREFACE. 



recommends the ftudy of them, yet he 

 makes ufe of motives that have no relation 

 to the common purpofes of Ufe. 



When Kepler, from a blind and ftrong 

 impulfe merely to find analogies in nature, 

 difcovered that famous one between the 

 diftances of the feveral planets from the 

 fun, and the periods in v/hich they com- 

 pleat their revolutions ; of what importance 

 was it to him or to the world ? 



Again J when Galileo, puflied on by the 

 fame irrefiftible curiofity, found out the law 

 by which bodies fall to the earth, did he 

 or could he forefee that any good would 

 come from his ingenious theorems, or was 

 any immediate ufe made of them ? 



Yet had not the Greeks pufhed their ab- 

 ftradl fpeculations fo far ; had not Kepler 

 and Galileo made the above mentioned dif- 

 coveries ^ we never could have feen the 

 greateft work that ever came from the 

 hands of man. Every one will guefs that 

 i mean Sir Ifaac Newton's Principia. 



Some obfcure perfon, whofe name is not 

 fo much as known, diverting himfelf idly 



as 



