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For, granting the nebula and its potential life, the 

 question, whence came they ? would still remain to 

 baffle and bewilder us. And with regard to the ages of 

 forgetfulness which lie between the conscious life of the 

 nebula and the conscious life of the earth, it is but an 

 extension of that forgetfulness which preceded the birth 

 of us all. Those who hold the doctrine of evolution 

 are by no means ignorant of the uncertainty of their 

 data, and they yield no more to it than a provisional 

 assent. They regard the nebular hypothesis as proba- 

 ble, and in the utter absence of any evidence to prove 

 the act illegal, they extend the method of nature from 

 the present into the past. Here the observed uniform- 

 ity of nature is their only guide. Within the long range 

 of physical inquiry they have never discerned in nature 

 the insertion of caprice. Throughout this range the 

 laws of physical and intellectual continuity have run 

 side by side. Having thus determined the elements of 

 their curve in this world of observation and experiment, 

 they prolong that curve into an antecedent world, and 

 accept as probable the unbroken sequence of devel- 

 opment from the nebula to the present time. 



You never hear the really philosophical defenders of 

 the doctrine of uniformity speaking of impossibilities in 

 nature. They never say, what they are constantly 

 charged with saying, that it is impossible for the builder 

 of the universe to alter His work, Their business is 

 not with the possible, but the actual j not with a world 

 which might be, but with a world which is. This they 

 explore with a courage not unmixed with reverence, and 

 according to methods which, like the quality of a tree, 

 are tested by their fruits. They have but one desire 

 to know the truth. They have but one fear to believe 



