A HISTORY OF SCIENCE 



nine, and the counter - earth supplied the missing 

 body. 



The precise genesis and development of this idea 

 cannot now be followed, but that it was prevalent about 

 the fifth century B.C. as a Pythagorean doctrine can- 

 not be questioned. Anaxagoras also is said to have 

 taken account of the hypothetical counter-earth in his 

 explanation of eclipses; though, as we have seen, he 

 probably did not accept that part of the doctrine 

 which held the earth to be a sphere. The names of 

 Philolaus and Heraclides have been linked with cer- 

 tain of these Pythagorean doctrines. Eudoxus, too, 

 who, like the others, lived in Asia Minor in the fourth 

 century B.C., was held to have made special studies of 

 the heavenly spheres and perhaps to have taught that 

 the earth moves. So, too, Nicetas must be named 

 among those whom rumor credited with having taught 

 that the world is in motion. In a word, the evidence, 

 so far as we can garner it from the remaining frag- 

 ments, tends to show that all along, from the time of 

 the early Pythagoreans, there had been an under- 

 current of opinion in the philosophical world which 

 questioned the fixity of the earth ; and it would seem 

 that the school of thinkers who tended to accept the 

 revolutionary view centred in Asia Minor, not far from 

 the early home of the founder of the Pythagorean doc- 

 trines. It was not strange, then, that the man who 

 was finally to carry these new opinions to their logical 

 conclusion should hail from Samos. 



But what was the support which observation could 

 give to this new, strange conception that the heavenly 

 bodies do not in reality move as they seem to move, 



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