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 hisown. 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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