CELESTIAL MOVERS IN MEDIEVAL PHYSICS 153 



modernity of medieval science. Even if there should happen 

 to be considerable similarity between some aspect of medieval 

 science and a current scientific view, this would be no more 

 than an interesting curiosity, unless we come to grip with an 

 objective philosophical problem and analyze the issues his- 

 torically and scientifically. 



A short paper such as this cannot sketch even in broad out- 

 lines a picture of medieval astronomy or the history of its 

 development.' All that can be attempted here is an examina- 

 tion of the problem as seen by each of the three Dominican 

 Masters consulted by the Master General, and an explanation 

 of the views proposed, especially in their response to the oflficial 

 questionnaire. Since our purpose here is to understand the 

 medieval view, we need not be concerned about the true his- 

 torical intent of ancient sources, but only about how the 

 medieval schoolmen interpreted them. That is to say, it is not 

 essential here to understand what Plato, Aristotle, Ptolemy or 

 Al-Bitruji really meant; it is essential only that we understand 

 what St. Albert, St. Thomas and Kilwardby thought them to 

 mean. There is always the possibility that these great school- 

 men misunderstood or misinterpreted their sources, but this 

 makes little, if any, difference to the medieval view of the 

 scientific problem. 



Preliminary Observations 



In the traditional division of the speculative sciences derived 

 from Plato and Aristotle, astronomy occupied a peculiar posi- 

 tion. By astronomy we do not mean the elementary calculation 

 of movable feast days, the Epact or the Golden Number; nor do 

 we mean identification of the signs of the zodiac or prognosti- 

 cations from conjunctions. By astronomy is meant the theo- 

 retical sciences which attempts to make celestial phenomena 

 intelligible by means of mathematical principles. The peculiar 

 position of this theoretical science can be recognized clearly in 

 the writings of the three consultors. 



'' An outline can be found in P. Duhem, Le Systeme du Monde (Paris: Hermann, 

 1954). vol. III. 



