A HISTORY OF SCIENCE 



ciated in some way with the change of the sun's place 

 in the heavens must, in time, have impressed itself 

 upon even a rudimentary intelligence. It is hardly 

 necessary to add that this is not meant to imply any 

 definite knowledge of the real meaning of the seeming 

 oscillations of the sun. We shall see that, even at 

 a relatively late period, the vaguest notions were 

 still in vogue as to the cause of the sun's changes of 

 position. 



That the sun, moon, and stars move across the 

 heavens must obviously have been among the earliest 

 scientific observations. It must not be inferred, how- 

 ever, that this observation implied a necessary con- 

 ception of the complete revolution of these bodies about 

 the earth. It is unnecessary to speculate here as to 

 how the primitive intelligence conceived the transfer 

 of the sun from the western to the eastern horizon, to 

 be effected each night, for we shall have occasion to 

 examine some historical speculations regarding this 

 phenomenon. We may assume, however, that the 

 idea of the transfer of the heavenly bodies beneath the 

 earth (whatever the conception as to the form of that 

 body) must early have presented itself. 



It required a relatively high development of the ob- 

 serving faculties, yet a development which man must 

 have attained ages before the historical period, to note 

 that the moon has a secondary motion, which leads it 

 to shift its relative position in the heavens, as regards 

 the stars ; that the stars themselves, on the other hand, 

 keep a fixed relation as regards one another, with the 

 notable exception of two or three of the most brilliant 

 members of the galaxy, the latter being the bodies 



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