SCIENCE AND PROGRESS 



Nicetas of Syracuse, as Theophrastus says, believed that 

 the heavens, the sun, the moon, the stars in brief, all 

 things above stand still; alone, the earth, of all things in 

 the world, moves. Because it is rapidly turning and twist- 

 ing upon its axis, it gives the effect of the whole sky mov- 

 ing, and that the earth stands. 1 



This was a long time before the famous, but 

 probably apocryphal, " E pur si muove" (And yet 

 it does move), of the aged Galileo. 



Moreover, the ingenuity of mind displayed by 

 some of these early investigators must ever com- 

 mand the admiration of intelligent men. At the 

 risk of a slight digression, I will venture to note 

 two instances which are most striking. 



Aristarchus of Alexandria describes in his trea- 

 tise, On the Magnitude and Distances of the Sun and 

 the Moon, still extant, his methods of calculation. 

 If the moon shines by the light of the sun, to an 

 observer on a line between these two bodies the 

 moon would always appear "full." But if the 

 observer's position be shifted to a point on a line 

 at right angles to this, and intersecting the earth 

 and the moon, the latter's disk would appear just 

 cut in two. The earth is at such a point when the 

 moon appears to us "half full." By then meas- 

 uring the angle formed by lines drawn from the 

 earth to the sun and to the moon, it is possible to 



l Academica, lib. iv., cap. 39. 

 7 



