A HISTORY OF SCIENCE 



though he confessed no faith in such predictions. " Ye 

 otherwise philosophers," he said, "ye censure this 

 daughter of astronomy beyond her deserts; know ye 

 not that she must support her mother by her charms." 



Once astrology had become an established practice, 

 any considerable knowledge of astronomy was un- 

 necessary, for as it was at best but a system of good 

 guessing as to future events, clever impostors could 

 thrive equally well without troubling to study astron- 

 omy. The celebrated astrologers, however, were usu- 

 ally astronomers as well, and undoubtedly based many 

 of their predictions on the position and movements of 

 the heavenly bodies. Thus, the casting of a horo- 

 scope that is, the methods by which the astrologers 

 ascertained the relative position of the heavenly bodies 

 at the time of a birth was a simple but fairly exact 

 procedure. Its basis was the zodiac, or the path traced 

 by the sun in his yearly course through certain con- 

 stellations. At the moment of the birth of a child, 

 the first care of the astrologer was to note the partic- 

 ular part of the zodiac that appeared on the horizon. 

 The zodiac was then divided into " houses " that is, 

 into twelve spaces on a chart. In these houses were 

 inserted the places of the planets, sun, and moon, with 

 reference to the zodiac. When this chart was com- 

 pleted it made a fairly correct diagram of the heavens 

 and the position of the heavenly bodies as they would 

 appear to a person standing at the place of birth at a 

 certain time. 



Up to this point the process was a simple one of 

 astronomy. But the next step the really important 

 one that of interpreting this chart, was the one which 



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