COSMIC PHILOSOPHY 



man appears to be walking westward, he is really 

 being carried eastward by the earth's rotation at 

 the rate of iooo miles an hour. Besides this, 

 the earth's orbital motion is carrying him west- 

 ward at the differential rate of 67,000 miles an 

 hour. Meanwhile the motion of the solar sys- 

 tem toward the constellation Hercules is all the 

 time bearing him in a direction neither east nor 

 west. While, if we could comprehend in a sin- 

 gle view the dynamic relations of the entire 

 sidereal universe, we should find that even the 

 enormous factors already taken into the account 

 would help us but little toward determining the 

 resultant direction in which the man is moving. 

 The comparative ease with which astronomy 

 ascertains the direction of the motions with 

 which it deals is due to our ability to isolate 

 ourselves theoretically from an indefinitely ex- 

 tended universe of environing bodies; and this 

 is due to the principle, established by Galileo, 

 that the relative motions of the parts of an ag- 

 gregate are not affected by the motion of the 

 whole. If we could include in the problem the 

 entire knowable universe, we should doubtless 

 find the real motions of a planet as impossible 

 to calculate mathematically as are now the mo- 

 tions of a corpuscle of nerve-substance when 

 thrown out of equilibrium by an act of thinking. 

 Nevertheless because of this principle that 

 the relative motions of parts may be calculated 

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