THE GOSPEL OF NATURE 



the air called sound, the sense of smell by those 

 emanations called odors. There are probably other 

 vibrations and emanations that we have no senses 

 for because our well-being does not demand them. 

 We think it reasonable that a stone should fall 

 and that smoke should rise because we have never 

 known either of them to do the contrary. We think 

 it reasonable that fire should burn and that frost 

 should freeze, because this accords with universal 

 experience. Thus, there is a large order of facts 

 that are reasonable because they are invariable : the 

 same effect always follows the same cause. Our 

 reason is developed and disciplined by observing 

 the order of Nature; and yet human rationality is of 

 another order from the rationality of Nature. Man 

 learns from Nature how to master and control her. 

 He turns her currents into new channels; he spurs 

 her in directions of his own. Nature has no economic 

 or scientific rationality. She progresses by the 

 method of trial and error. Her advance is symbol- 

 ized by that of the child learning to walk. She ex- 

 periments endlessly. Evolution has worked all 

 around the horizon. In feeling her way to man she 

 has produced thousands of other forms of life. The 

 globe is peopled as it is because the creative energy 

 was blind and did not at once find the single straight 

 road to man. Had the law of variation worked only 

 in one direction, man might have found himself the 

 sole occupant of the universe. Behold the varieties 



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