120 PHYSICAL SCIENCE BK. m 



earth is interchangeable in its elements. So all this 

 air that she has exhaled in her interior, since it is 

 not taken up by the free atmosphere, condenses and 

 is forthwith converted into moisture. 



1 THERE you have the first cause of the origin of 

 underground water. You may add the more 

 general principle that all elements arise from all : 

 air comes from water, water from air ; fire from air, 

 air from fire. So why should not earth be formed 

 from water, and conversely water from earth? If 

 the earth is capable of transmutation into other 

 elements, water must be one of them, in fact, the 

 most suitable of them. The two things are cognate ; 

 both are heavy, condensed, both driven by nature 

 down to the very confines of the universe. Earth 

 is formed from water ; why not water from earth in 

 like manner? 



But, you say, the rivers are too large to be 

 accounted for in this way. Well, after you have 

 considered the size of the rivers, just look at the 



2 size of the reservoir whence they issue. Are you 

 surprised that a fresh supply of water is always 

 forthcoming for them, since they flow on for ever, 

 some even rushing down their channel with im- 

 petuous haste ? Surely you might as well be 

 surprised, when the winds drive hither and thither 

 the whole atmosphere, that the supply of air does 

 not fail, but flows on day and night unceasingly. 

 And the wind, remember, is not confined to a definite 

 channel, as rivers are, but goes with wide sweep 

 over the broad expanse of heaven. You might 



