156 THE GREEK ASTRONOMY. 



them into his own country. His knowledge, indeed, 

 must have been a great deal more advanced than 

 that which we are now describing, if it be true, 

 as is asserted, that he predicted an eclipse. But 

 his having done so is not very consistent with what 

 we are told of the steps which his successors had 

 still to make. 



The Circle of the Signs, in which the sun moves 

 among the stars, is obliquely situated with regard 

 to the circles in which the stars move about the 

 poles. Pliny 39 states that Anaximander 40 , a scholar 

 of Thales, was the first person who pointed out 

 this obliquity, and thus, as he says, "opened the 

 gate of nature." Certainly the person who first 

 had a clear view of the nature of the sun's path in 

 the celestial sphere, made that step which led to 

 all the rest ; but it is difficult to conceive that the 

 Egyptians and Chaldeans had not already advanced 

 so far. 



The diurnal motion of the celestial sphere, and 

 the motion of the moon in the circle of the signs, 

 gave rise to a mathematical science, the Doctrine 

 of the Sphere, which was one of the earliest 

 branches of applied mathematics. A number of 

 technical conceptions and terms were soon intro- 

 duced. The Sphere of the heavens was conceived 

 to be complete, though we see but a part of it ; it 



38 Lib. ii. c. (viii.) 

 40 Plutarch, De Plac. Phil. lib. ii. cap. xii. says Pythagoras 

 was the author of this discovery. 



