THE RHYTHMIC UNIVERSE 377 



appears to be related to causal factors on a more and more cos- 

 mic scale, certainly suggests the presence of a real entity or enti- 

 ties moving in a constant manner in such a way as to cause 

 periodic variation. The hypothesis of ultimate regular motions 

 in the universe causing a regular periodicity is, as is known, 

 that of Aristotle and St. Thomas Aquinas. This hypothesis 

 attempted to explain the simultaneous effect of constancy and 

 periodicity as derived from the perpetual, regular, apparent 

 motion of the heavenly bodies such as the fixed stars and the 

 planets; the periodicity in terrestrial organic life was thought 

 to be caused by the apparent northerly and southerly variations 

 of the sun and the planets in the zodiacal circle. It should be 

 noted that this hypothesis, already in St, Thomas' day, had 

 extended beyond the limit of the fixed stars in seeking to locate 

 the ultimate corporeal source of cosmic motion, for the detec- 

 tion of the precession of the equinoxes required the positing 

 of a further motion beyond that of the fixed stars. 



17 



^'^ " From the perpetuity of generation [Aristotle] concludes to the perpetuity of 

 celestial motion. . . . He concludes that if something remains the same throughout 

 the course of generation, it is necessary for something to remain numerically always 

 the same, acting in the same way, in order to cause perpetuity. But nothing in the 

 realm of generation and corruption could be a cause of the perpetuity which is found 

 in generation and corruption, since none of these things exist always, nor could all 

 of them taken together be such a cause, since they do not all exist at one time, 

 as is shown in Physics VIII. It remains, therefore, that there must be some 

 perpetual agent which acts continuously in a uniform way to bring about perpetuity. 

 And this is the ' first heaven ' which moves and resolves all things by a diurnal 

 motion. 



" But since that which continuously acts m the same way solely causes an effect 

 which remains constant, while in those things which are generated and corrupted 

 there appear effects which do not always remain constant since at one time they are 

 generated and at another time corrupted, it is therefore necessary, if there is to be 

 generation and corruption in the lower [i. e. terrestrial] beings, to posit some agent 

 which varies in its activity. And this agent he states to be the body which moves 

 in reference to the oblique circle called the Zodiac. 



" Since this circle declines in both directions from the equinoxial circle, it is 

 necessary that the body moving in a circle through the Zodiac be sometimes nearer 

 and sometimes farther away, and for this reason it causes contrary effects by its 

 nearness and farness. We indeed perceive that those things which are generated as 

 the sun approaches are corrupted when the sun recedes, for example, the various 

 herbages which come forth in the spring and dry up in the fall. The sun and the 



