PRELUDE TO THE EPOCH OF NEWTON. 137 



men's views and the traditions of professors have 

 been so long dissevered, are, in fact, one and the 

 same thing, and compose one body of science." It 

 must be allowed that, however erroneous might be 

 the points of Bacon's positive astronomical creed, 

 these general views of the nature and position of 

 the science are most sound and philosophical. 



(Kepler.} In his attempts to suggest a right 

 physical view of the starry heavens and their rela- 

 tion to the earth, Bacon failed, along with all the 

 writers of his time. It has already been stated 

 that the main cause of this failure was the want 

 of a knowledge of the true theory of motion ;- 

 the non-existence of the science of Dynamics. At 

 the time of Bacon and Kepler, it was only just 

 beginning to be possible to trace the heavenly 

 motions to the laws of earthly motion, because the 

 latter were only just then divulged. Accordingly, 

 we have seen that the whole of Kepler's physical 

 speculations proceed upon an ignorance of the 

 first law of motion, and assume it to be the main 

 problem of the physical astronomer to assign the 

 cause which keeps up the motions of the planets. 

 Kepler's doctrine is, that a certain Force or Virtue 

 resides in the sun, by which all bodies within his 

 influence are carried round him. He illustrates 2 

 the nature of this Virtue in various ways, com- 

 paring it to Light, and to the Magnetic Power, 

 which it resembles in the circumstances of operat- 



3 De Stella Martin, P. 3, c. xxxiv. 



