BOOK II. VII. 47-vni. 49 



the sun being taken away from the earth by the moon 

 intervening and from the moon by the earth : at the 

 transit of the former a sudden shadow passes over 

 the earth, and in return the shadow of the latter 

 dims the heavenly body (the moon), and the dark- 

 ness is merely the earth's shadow, but the shape of 

 the shadow is conical, resembhng a spinning-top 

 upside doAvn, as it impinges only with its point and 

 does not go beyond the altitude of the moon, because 

 no other star is obscured in the same way,** and a 

 conical figiu-e always tapers off into a point : that 

 shadows are made to disappear by distance is proved 

 when birds fly to extreme heights. Consequently 

 the frontier between the moon and the other 

 heavenly bodies is at the point where the air ends 

 and the aether begins. All the space above the moon 

 is clear and filled with continual Hght, but to us the 

 stars are \dsible through the night in the same way 

 as other hghts in shadows. And these are the 

 reasons why the moon wanes in the night-time ; 

 but both of her wanings are irregular and not monthly, 

 because of the slant of the zodiac and the widely 

 varying curves of the moon's course, as has been 

 stated, the motion of the heavenly bodies not always 

 tallying in minute fractional quantities. 



VIII. This theory leads mortal minds upward to Thesun. 

 heaven, and discloses to their observation from that 

 height, as it were, the greatness of the three greatest 

 parts of the universe ; clearly it would not be possible 

 for the whole of the sun to be ecHpsed from the earth 

 by the passage of the moon between them if the earth 

 were larger than the moon. The vast size of the sun 

 will be showTi ^ with the more certainty from the 

 two bodies, so that there is no need to investigate 



199 



