THE BEGINNINGS OF GREEK SCIENCE 



equal to its own height at the same moment. It re- 

 mains then but to measure the length of this shadow 

 to determine the height of the object. Such feats as 

 this evidence the practicality of the genius of Thales. 

 They suggest that Greek science, guided by imagina- 

 tion, was starting on the high-road of observation. 

 We are told that Thales conceived for the first time the 

 geometry of lines, and that this, indeed, constituted his 

 real advance upon the Egyptians. We are told also 

 that he conceived the eclipse of the sun as a purely 

 natural phenomenon, and that herein lay his advance 

 upon the Chaldean point of view. But if this be true 

 Thales was greatly in advance of his time, for it will be 

 recalled that fully two hundred years later the Greeks 

 under Nicias before Syracuse were so disconcerted by 

 the appearance of an eclipse, which was interpreted 

 as a direct omen and warning, that Nicias threw away 

 the last opportunity to rescue his army. Thucydides, 

 it is true, in recording this fact speaks disparagingly 

 of the superstitious bent of the mind of Nicias, but 

 Thucydides also was a man far in advance of his 

 time. 



All that we know of the psychology of Thales is 

 summed up in the famous maxim, "Know thyself," 

 a maxim which, taken in connection with the proven 

 receptivity of the philosopher's mind, suggests to us a 

 marvellously rounded personality. 



The disciples or successors of Thales, Anaximander 

 and Anaximenes, were credited with advancing knowl- 

 edge through the invention or introduction of the sun- 

 dial. We may be sure, however, that the gnomon, 

 which is the rudimentary sundial, had been known 



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