64 THE WORLD MACHINE 



now. And this idea held the field for a long time. Much that 

 is among the highest in human development had been attained 

 before men ceased so to believe the Parthenon had been built, 

 the songs of Homer sung, the tragedies of Euripides enacted ; 

 Socrates had drunk of the hemlock. 



But to men habituated, like the early shepherds, to watch 

 the heavens night by night came suggestions of another sort. 

 The vault of the sky seems a sphere. The stars seem to revolve 

 in circles, the horizon is always round, the shadow cast by the 

 earth in eclipse is round ; it is a little strange that the early 

 astronomers should ever have had any other idea than that 

 the earth is a sphere as well. 



This was certainly the teaching of Thales, one of the seven 

 wise men ; he had it undoubtedly from the Nile priests, among 

 whom he had dwelt ; they, we may surmise, may have been 

 teaching it to the initiate for ten or twenty centuries before ; 

 perhaps for a period more distant from Thales than Thales 

 from us. And the astronomy of the Chaldeans was not less 

 ancient. Nevertheless their doctrines were not held by the 

 generality of men. 



We may fix with a fair degree of certainty when they came 

 in, at least to European thought. They were not known or 

 not accepted at the time of Athens in her glory, the Athens 

 of Pericles and Phidias. They were accepted as a matter of 

 fact by Aristotle a century later. Whatever their force, they 

 did not prevail in the all-embracing mind of Democritus of 

 Abdera he who, save Archimedes, was perhaps the greatest 

 intellect of antiquity. They had certainly been worked out 

 in full detail by Bion, his pupil, if we may trust to a hint in 

 the frugal pages of Diogenes Laertius. 



Of this Bion the mathematician, and native, like Democritus, 

 of Abdera, we have only a line. 



" He was the first person who asserted that there were 

 countries where there was day for six months and night for 

 six months." 



That was all that remained of him to fame, when in the 

 second century of our era Diogenes of Laerte came to write 

 that curious history to which the larger part of our knowledge 

 of the ancient philosophers is due. But consider for a moment 

 all that this assertion of Bion's implies. There is not the 

 slightest possibility that the land of the Midnight Sun was then 



