xi EFFECT OF TREE FELLING 123 



which was a city in the island of Crete, the wells 

 and lakes disappeared, because the land ceased to 

 be tilled after the destruction of the city ; but after 

 it had got back its tillers, it recovered its waters 

 also. He sets down as the cause of the dry ness, 

 that the earth had got hidebound and quite hard, 

 and not being stirred could not transmit to the 

 underground reservoirs the rain that fell. But if 

 this is true, how comes it that we see springs in 

 great plenty in the most desert ground? In fact, 

 one finds a great deal more ground that began to 

 be tilled on account of the abundance of water than 

 that began to have an abundant supply of water 

 because it was tilled. You may be quite sure that 

 it is not mere rain water that is carried down in our 

 greatest rivers, navigable by large vessels from their 

 very source, 1 as is proved by the fact that the flow 

 from the fountain-head is uniform winter and summer. 

 Rainfall may cause a torrent, but it cannot maintain 

 the steady, constant flow of a full river. Rains cannot 

 produce, they can only enlarge and quicken, a river. 



XII 



LET us, if you please, go into the matter a little 

 more deeply, and you will soon see that you have 

 no cause to put further questions, once you reach 

 the true origin of rivers. A river is, of course, 

 formed by a supply of water that is always constant. 

 If you ask me, therefore, how water is produced, I 

 will ask in my turn how air or earth is produced. 

 If there are four elements in nature, you are not 

 entitled to ask where water, one of them, comes 



1 The text seems to be at fault, but the argument is quite clear. 



