of learned men. The student was taught from the 

 beginning of his work to look upon authority as the 

 foundation of his beliefs. The older the authority the 

 greater the weight it carried. So effective was this 

 teaching that it seems never to have occurred to indi- 

 vidual men that they had all the opportunities ever 

 enjoyed by Aristotle of discovering truth, with the 

 added advantage of all his knowledge to begin with. 

 Advanced as was the development of formal logic, that 

 practical logic was wanting which could see that the 

 last of a series of authorities, every one of which 

 rested on those which preceded il, could never form a 

 surer foundation for any doctrine than that supplied 

 by its original propounder. 



The result of this view of knowledge was that, 

 although during the fifteen centuries following the death 

 of the geometer of Syracuse great universities were 

 founded at which generations of professors expounded 

 all the learning of their time, neither professor nor 

 student ever suspected what latent possibilities of good 

 were concealed in the most familiar operations of nature. 

 Every one felt the wind blow, saw water boil and heard 

 the thunder crash, but never thought of investigating 

 the forces here at play. Up to the middle of the fif- 

 teenth century the most acute observer could scarcely 

 have seen the dawn of a new era. 



In view of this state of things it must be regarded 

 as one of the most remarkable facts in evolutionary 

 history that four or five men, whose mental constitution 

 was either typical of the new order of things or who 

 were powerful agents in bringing it about, were all 



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