91 



a moment's consideration will evince the 

 error of this supposition. Places abound- 

 ing in lakes and pools are generally the 

 highest in their respective countries; and 

 without such a provision of nature the 

 world could not be supplied with rivers, 

 which take their source in the highest 

 mountains, and after innumerable checks 

 to retard and expand their waters, they 

 gradually descend towards the sea. If 

 nature be the model for art in the com- 

 position of Landscape, we must imitate 

 her process, as well as her effects. Water, 

 by its own power of gravitation, seeks 

 the lowest ground, and runs along the 

 valleys.^ If in its course the water meets 



y Indeed I have sometimes fancied, that as action 

 and reaction are ahke, and as cause and effect often 

 change their situations, so valleys are increased in depth 

 by the course of waters perpetually passing along them: 

 thus, if the water only displaces one inch of soil in each 

 year, it will amount to 500 feet in 6000 years; and 

 this is equal to the deepest valleys in the world. In 

 loose soils, the sides of the hiUs will gradually wash 

 down, and form open valleys; in hard soils they will 

 become narrow valleys, but ravines I suppose to be the 

 effect of sudden convulsions from fire or steam, and 

 not made by any gradual abrasion of the surface. 



