ALEXANDRIAN OR HELLENISTIC PERIOD 



school were at their height. Hipparchus, at a later 

 day, was enabled to compare his own observations 

 with those made by Aristarchus, and, as we have just 

 seen, his work was well known to so distant a contem- 

 porary as Archimedes. Yet the facts of his life are 

 almost a blank for us, and of his writings only a single 

 one has been preserved. That one, however, is a most 

 important and interesting paper on the measurements 

 of the sun and the moon. Unfortunately, this paper 

 gives us no direct clew as to the opinions of Aristarchus 

 concerning the relative positions of the earth and sun. 

 But the testimony of Archimedes as to this is unequiv- 

 ocal, and this testimony is supported by other rumors 

 in themselves less authoritative. 



In contemplating this astronomer of Samos, then, 

 we are in the presence of a man who had solved in its 

 essentials the problem of the mechanism of the solar 

 system. It appears from the words of Archimedes that 

 Aristarchus had propounded his theory in explicit 

 writings. Unquestionably, then, he held to it as a posi- 

 tive doctrine, not as a mere vague guess. We shall 

 show, in a moment, on what grounds he based his 

 opinion. Had his teaching found vogue, the story of 

 science would be very different from what it is. We 

 should then have no tale to tell of a Copernicus coming 

 upon the scene fully seventeen hundred years later 

 with the revolutionary doctrine that our world is not 

 the centre of the universe. We should not have to 

 tell of the persecution of a Bruno or of a Galileo for 

 teaching this doctrine in the seventeenth century of an 

 era which did not begin till two hundred years after 

 the death of Aristarchus. But, as we know, the teach- 



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