132 THE GREEK ASTRONOMY. 



Several of the propositions contained in the former of these treatises 

 are still necessary to be understood, as fundamental parts of astronomy 



The work of Euclid, just mentioned, is of the same kind. Delam- 

 bre 47 finds in it evidence that Euclid was merely a book-astronomer, 

 who had never observed the heavens. 



We may here remark the first instance of that which we shall find 

 abundantly illustrated in every part of the history of science ; that man 

 is prone to become a deductive reasoner ; that as soon as he obtains 

 principles which can be traced to details by logical consequence, he 

 sets about forming a body of science, by making a system of such 

 reasonings. Geometry has always been a favorite mode of exercising 

 this propensity : and that science, along with Trigonometry, Plane 

 and Spherical, to which the early problems of astronomy gave rise, 

 have, up to the present day, been a constant field for the exercise of 

 mathematical ingenuity ; a few simple astronomical truths being as- 

 sumed as the basis of the reasoning. 



Sect. 9. The Globular Form of the Earth. 



THE establishment of the globular form of the earth is an important 

 step in astronomy, for it is the first of those convictions, directly 

 opposed to the apparent evidence of the senses, which astronomy 

 irresistibly proves. To make men believe that up and down are differ- 

 ent directions in different places ; that the sea, which seems so level, 

 is, in fact, convex; that the earth, which appears to rest on a solid 

 foundation, is, in fact, not supported at all ; are great triumphs both of 

 the power of discovering and the power of convincing. We may 

 readily allow this, when we recollect how recently the doctrine of the 

 antipodes, or the existence of inhabitants of the earth, who stand on 

 the opposite side of it, with their feet turned towards ours, was con- 

 sidered both monstrous and heretical. 



Yet the different positions of the horizon at different places, neces- 

 sarily led the student of spherical astronomy towards this notion of the 

 earth as a round body. Anaximander 48 is said by some to have held 

 the earth to be globular, and to be detached or suspended ; he is also 

 stated to have constructed a sphere, on which were shown the extent 

 of land and water. As, however, we do not know the arguments upon 

 which he maintained the earth's globular form, we cannot judge of the 



47 Ast. Anc. p. 53. See Brucker, Hist. Pldl. vol. i. p. 436. 



