72 THE PATH OF SCIENCE 



Startling contrast to that which he ^vrote on physics. In his 

 discussion of one set of observations, we might hear Bacon or 

 Newton ^vriting t^\o thousand years later: "... the facts 

 have not yet been sufficiently grasped; if they ever are, then 

 credit must be given to observations rather than to theories 

 and to theories only in so far as they are confirmed by the 

 observed facts." 



Aristotle was the tutor of Alexander the Great. After the 

 death of Alexander in 323 b.c, his general, Ptolemy, became 

 king of Egypt and established his capital at Alexandria. In 

 Alexandria, Ptolemy II founded the Museum, in which the 

 personal schools of Plato and Aristotle were developed into 

 a university. And there arose the greatest school of the 

 ancient world, in which most of the best scientists of the time 

 were professors. At the Museum, Euclid established his sys- 

 tem of geometry, which became the standard of the world 

 for more than two thousand years; Aristarchus ^vas the lead- 

 ing astronomer; Archimedes, the outstanding mathematician 

 and physicist. Archimedes himself came from Syracuse, to 

 w^hich he returned after his studies in Alexandria. Era- 

 tosthenes made such precise observations in astronomy that 

 he was able to calculate the diameter of the earth with con- 

 siderable accuracy and to elucidate the necessity for the Julian 

 calendar, with its Leap Year. An even more accurate observer 

 was Hipparchus, who discovered the precession of the equi- 

 noxes and established theoretical astronomy in the form that 

 it retained until the time of Copernicus. The civilization of 

 Alexandria was, however, doomed to collapse. The history 

 of the Ptolemies is one of steadily worsening government 

 until finally the Romans absorbed the fragments of the 

 Alexandrine Empire. 



The prevalent philosophy among the Roman leaders was 

 Stoicism, ^vhich laid great stress on conduct and duty and 

 had a completely rigid conception of nature. The Epicurean 

 philosophy was less widely adopted but had gieater influence 

 on those few Romans ^vho were interested in science or in 

 the writing of philosophy. Of these, by far the best known 



