PRELUDE TO THE EPOCH OF HIPPARCHUS. 179 



no one would tolerate such anomaly in the move- 

 ments, even of a man, who was decent and orderly. 

 The occasions of life, however, are often reasons 

 for men going quicker or slower, but in the incor- 

 ruptible nature of the stars, it is not possible that 

 any cause can be alleged of quickness and slow- 

 ness. Whereupon they propounded this question, 

 how the phenomena might be represented by 

 equable and circular motions." 



These conjectures and assumptions led natu- 

 rally to the establishment of the various parts of 

 the Theory of Epicycles. It is probable that this 

 theory was adopted with respect to the planets 

 at or before the time of Plato. And Aristotle 

 gives us an account of the system thus devised 7 . 

 "Eudoxus," he says," "attributed four spheres to 

 each Planet: the first revolved with the fixed stars 

 (and this produced the diurnal motion) ; the second 

 gave the planet a motion along the ecliptic (the 

 mean motion in longitude) ; the third had its axis 

 perpendicular 8 to the ecliptic (and this gave the 

 inequality of each planetary motion) ; the fourth 

 produced the oblique motion transverse to this 

 (the motion in latitude)." He is also said to have 

 attributed a motion in latitude and a correspond- 



7 Metaph. xi. 8. 



8 Aristotle says " has its poles in the ecliptic," but this must 

 be a mistake of his. He professes merely to receive these opinions 

 from the professed astronomers "CK TJS olneiordrri's <pi\o<ro(pia<: 



N2 



