10 THE HISTORY OF SCIENCE 



equinoxes follow each other at intervals of a few sec- 

 onds less than a year. 



A second motive that influenced the Babylonian 

 priests in studying the movements of the heavenly 

 bodies was the hope of foretelling events. The plan- 

 ets, seen to shift their positions with reference to the 

 other heavenly bodies, were called messengers, or 

 angels. The appearance of Mars, perhaps on account 

 of its reddish color, was associated in their imagina- 

 tions with war. Comets, meteors, and eclipses were 

 considered as omens portending pestilence, national 

 disaster, or the fate of kings. The fortunes of in- 

 dividuals could be predicted from a knowledge of 

 the aspect of the heavens at the hour of their birth. 

 This interest in astrology, or divination by means of 

 the stars, no doubt stimulated the priests to make 

 careful observations and to preserve religiously the 

 record of astronomical phenomena. It was even es- 

 tablished that there is a cycle in which eclipses, solar 

 and lunar, repeat themselves, a period (saros) some- 

 what more than eighteen years and eleven months. 

 Moreover, from the Babylonians we derive some of 

 our most sublime religious and scientific concep- 

 tions. They held that strict law governs the appar- 

 ently erratic movements of the heavenly bodies. 

 Their creation myth proclaims: "Merodach next 

 arranged the stars in order, along with the sun and 

 moon, and gave them laws which they were never to 

 transgress." 



The mathematical knowledge of the Babylonians is 

 related on the one hand to their astronomy and on the 

 other to their commercial pursuits. They possessed 

 highly developed systems of measuring, weighing, 



