v SCIENTIFIC DISCO VER Y GRAD UAL 2 3 1 



to remove the veil that hid nature, and, not satisfied 

 with a superficial view, to look beneath the surface 

 and dive into the secrets of the gods. A great con- 

 tribution to discovery was made by the man who 

 first conceived the hope of its possibility. We 

 must, therefore, listen indulgently to the ancients. 

 No subject is perfected while it is but beginning. 

 The truth holds not merely of the subject we are 

 dealing with, the greatest and most complicated of 

 all, in which, however much may be accomplished, 

 every succeeding age will still find something fresh 

 to accomplish. It holds alike in every other 

 concern ; the first principles have always been a 

 long way off from the completed science. 



VI 



WATER is the first cause alleged: more authors than i 

 one adopt this view, but it is not stated by all in 

 the same terms. Thales of Miletus is convinced 

 that the whole earth floats, and is upborne by mois- 

 ture lying beneath it, which you may call either Ocean 

 or the great sea, or still mere elemental water of a 

 different character from the sea, the simple ingredient, 

 moisture. In these waves, in his opinion, the globe 

 is supported like some huge lumbering vessel in the 

 water which bears it. It is unnecessary for me to 2 

 reproduce his reasons for supposing that the heaviest 

 part of the world cannot be sustained in such a rare 

 and nimble element as air : for the earth's position 

 is not the question here but its movement. By way 

 of argument, to prove that water is the cause, he 

 adduces the fact that in every considerable earth- 

 quake, as a rule, new springs burst out. So if 



