We may say that all the forms in the non-living world come by chance, or by the action of the undirected irrational physical forces, mechanical or mechanico-chemical. There are not two kinds of forces shaping the earth's surface, but the same forces are doing two kinds of work, piling up and pulling down--aggregating and accumulating, and separating and disintegrating.
It is to me an interesting fact that the striking and beautiful forms in inorganic nature are not as a rule the result of a building-up process, but of a pulling-down or degradation process. A natural bridge, an obelisk, caves, canals, the profile in the rocks, the architectural and monumental rock forms, such as those in the Grand Cañon and in the Garden of the Gods, are all the result of erosion. Water and other aerial forces are the builders and sculptors, and the nature and structure of the material determine the form. It is as if these striking forms were inherent in the rocks, waiting for the erosive forces to liberate them. The stratified rocks out of which they are carved were not laid down in forms that appeal to us, but layer upon layer, like the leaves of a book; neither has the crumpling and deformation of the earth's crust piled them up and folded them in a manner artistic and suggestive. Yet behold what the invisible workmen have carved out of them in the Grand Cañon! It looks as though titanic architects and sculptors had been busy here for ages. But only little grains of sand and a vast multitude of little drops of water, active through geologic ages, were the agents that wrought this stupendous spectacle. If the river could have builded something equally grand and beautiful with the material it took out of this chasm! But it could not--poetry at one end of the series and dull prose at the other. The deposition took the form of broad, featureless, uninteresting plains--material for a new series of stratified rocks, out of which other future Grand Cañons may be carved. Thus the gods of erosion are the artists, while the builders of the mountains are only ordinary workmen.
This bit of nature which I call myself, and which I habitually think of as entirely apart from the nature by which I am surrounded, going its own way, crossing or defeating or using the forces of the nature external to it, is yet as strictly a part of the total energy we call nature as is each wave in the ocean, no matter how high it raises its crest, a part of the ocean. Our wills, our activities, go but a little way in separating us from the totality of things. Outside of the very limited sphere of what we call our spontaneous activities, we too are things and are shaped and ruled by forces that we know not of.
