ITS EARLIEST STAGES. 163 



earth, the whole earth had no such tendency ; that 

 the inequalities on the surface were so small as 

 not materially to affect the shape of so vast a 

 mass; that drops of water naturally form them- 

 selves into figures with a convex surface ; that the 

 end of the ocean would fall if it were not rounded 

 off; that we see ships, when they go out to sea, 

 disappearing downwards, which shows the surface 

 to be convex. These are the arguments still em- 

 ployed in impressing the doctrines of astronomy 

 upon the student of our own days ; and thus we 

 find that, even at the early period of which we 

 are now speaking, truths had begun to accumulate 

 which form a part of our present treasures. 



Sect. 10. The Phases of the Moon. 



WHEN men had formed a steady notion of the 

 moon as a solid body, revolving about the earth, 

 they had only further to conceive it spherical, and 

 to suppose the sun to be beyond the region of the 

 moon, and they w r ould find that they had obtained 

 an explanation of the varying forms which the 

 bright part of the moon assumes in the course of 

 a month. For the convex side of the crescent- 

 moon, and her full edge when she is gibbous, are 

 always turned towards the sun. And this expla- 

 nation, once suggested, would be confirmed, the 

 more it was examined. For instance, if there be 

 near us a spherical stone, on which the sun is 



M2 



