THE GOLDEN AGE OF GREECE 85 



extent of Democritus and the forerunner and exemplar of the 

 Roman Lucretius. This was Epicurus (342-270 B.C.), who, born 

 in Samos and educated in Athens and Asia Minor, became a 

 famous teacher and the head of a remarkable community "such 

 as the ancient world had never seen." The mode of life in this 

 community was not that of the so-called "epicures" of to-day, but 

 very plain, water the general drink, and barley bread the 

 general food. The magnetic personality of Epicurus held the 

 community together, and his chief work was a treatise on Nature 

 in thirty-seven books. Epicureanism is of interest in the history 

 of science chiefly because of its effect on its Roman exponent, the 

 poet Lucretius. Much of it was even a negation of science and 

 the scientific spirit. 



HERACLIDES. ROTATION OF THE EARTH. To Heraclides of 

 Pontus in the fourth century B.C. belongs the distinction of teach- 

 ing that the earth turns on its own axis from west to east in 24 

 hours. He had been connected with the Pythagoreans, and with 

 the schools of Plato and Aristotle. His work is known to us only 

 indirectly, none of his own writings having survived. He is said 

 also to have advanced the hypothesis that Venus and Mercury 

 revolve about the sun, being therefore at a distance from the 

 earth sometimes greater than the sun, sometimes less. Geminus 

 writing in the first half of the first century B.C. of the different 

 fields and points of view of astronomers and physicists, remarks : - 



For why do sun, moon and planets appear to move unequally? 

 Because, when we assume their circles to be excentric, or the stars to 

 move on an epicycle, the appearing anomaly can be accounted for, 

 and it is necessary to investigate in how many ways the phenomena 

 can be represented, so that the theory of the wandering stars may be 

 made to agree with the etiology in a possible manner. Therefore also 

 a certain Heraclides of Pontus stood up and said that also when the 

 earth moved in some way and the sun stood still in some way, could 

 the irregularity observed relatively to the sun be accounted for. 

 In general it is not the astronomer's business to see what by its nature 

 is immovable and of what kind the moved things are, but framing 

 hypotheses as to some things being in motion and others being fixed, 



