ITS EARLIEST STAGES. 159 



same kind. Delambre 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 rea- 

 sonings. Geometry has always been a favourite 

 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 assumed 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 astro- 

 nomy irresistibly proves. To make men believe 

 that up and down are different directions in dif- 

 ferent 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 sup- 



47 A. A. p. 53. 



