378 SISTER MARGARET ANN 



Needless to say, in considering the suppositions of Aristotle 

 as expounded by St. Thomas, it is not a question of urging 

 their literal acceptance, since even their authors did not con- 

 sider them to be demonstrated.^* Rather it is a matter of 

 considering them from the standpoint of their general intellec- 

 tual approach, an approach which accords well, for example, 

 with findings indicative of universal cosmic rhythms making 

 themselves felt in the periodicity of terrestrial organisms, since 

 it is an approach sensitive to the over-all rhythmicity of the 

 universe felt even in the smallest details of earthly life. This 



other planets move indeed through the zodiacal circle, but the fixed stars are said 

 to move around the zodiacal poles, and not around the equinoxial poles, as Ptolemy 

 shows. From the motion of these there is caused the generation and corruption of 

 all things generated and corrupted, but this is more evident in the case of the 

 motion of the sun." St. Thomas, In XII Metaph., lect. 6, nn. 2510-11. 



In another place St. Thomas explains: " One must consider that in the time of 

 Aristotle there had not been detected the motion of the fixed stars, which Ptolemy 

 sets down as moving from west to east around the poles of the Zodiac at the rate 

 of one degree every hundred years, in such a way that a full revolution of the 

 Zodiac is completed in thirty-six thousand years." (In II De caelo et mundo, 

 lect. 17, n. 7) This is the precession of the equinoxes which today is computed as 

 twenty-six thousand years. From the point of view of apparent motion, the fixed 

 stars in the various constellations of the Zodiac are in the course of a precession 

 from west to east in such a way that the vernal equinox, which several thousand 

 years ago took place when the sun was in Aries, now takes place, due to this 

 apparent motion of the signs from west to east, in the previous sign, that of Pisces. 

 At the present computation the rate of precession would be about 1.4° per hundred 

 years. St. Thomas then concludes: " Therefore the ancients laid down the sphere 

 of the fixed stars to be the first moving body, and to have only one motion, which 

 is the diurnal motion. But on the supposition that the fixed stars move, it is 

 necessary for this sphere to move with two motions, namely its own proper motion, 

 which is that of the fixed stars, and the diurnal motion, which is that of the 

 supreme sphere which is without stars." (Ibid.) I wish to express my gratitude to 

 Father Pierre Conway, O. P. for pointing out and translating these and subsequent 

 passages from St. Thomas. 



^® " These matters into which we inquire are difficult since we are able to perceive 

 little from their causes and the properties of these bodies are more remote from our 

 knowledge than the bodies themselves are distant from us in a purely spatial way." 

 (Ibid., n. 8) Speaking of the number of planetary motions, St. Thomas says, " We 

 shall state what the mathematicians have to say about this. . . . Whatever remains 

 unstated, however, shall have to be investigated by ourselves or taken on the 

 authority of those who investigate such things or developed later from the facts 

 now stated by those who treat these matters." (In XII Metaph., lect. 9, n. 2566) 



