136 HISTORY OF PHYSICAL ASTRONOMY. 



the heavenly bodies should be traced to their causes, 

 as well as reduced to rule, was felt by all persons 

 of active and philosophical minds as a pressing and 

 irresistible need, at the time of which we speak. 

 We have already seen how much this feeling had 

 to do in impelling Kepler to the train of laborious 

 research by which he made his discoveries. Perhaps 

 it may be interesting to point out how strongly 

 this persuasion of the necessity of giving a phy- 

 sical character to astronomy, had taken possession 

 of the mind of Bacon, who, looking at the pro- 

 gress of knowledge with a more comprehensive 

 spirit, and from a higher point of view than Kepler, 

 could have none of his astronomical prejudices, 

 since on that subject he was of a different school, 

 and of far inferior knowledge. In his " Description 

 of the Intellectual Globe," Bacon says that while 

 Astronomy had, up to that time, had it for her 

 business, to inquire into the rules of the heavenly 

 motions, and Philosophy, into their causes, "they 

 had both so far worked without due appreciation of 

 their respective tasks ; Philosophy neglecting facts, 

 and Astronomy claiming assent to her mathema- 

 tical hypotheses, which ought to be considered as 

 mere steps of calculation. " Since, therefore," he 

 continues 1 , "each science has hitherto been a slight 

 and ill-constructed thing, we must assuredly take 

 a firmer stand ; our ground being, that these two 

 subjects, which on account of the narrowness of 

 1 Vol. ix. 221. 



