376 INTRODUCTION. 



gress of inventions in the arts, which call out and 

 fix the distinctness of our conceptions of the re- 

 lations of natural phenomena. As men's minds 

 became clear, they became less servile: the per- 

 ception of the nature of truth drew men away from 

 controversies about mere opinion; when they saw 

 distinctly the relations of things, they ceased to 

 give their whole attention to what had been said 

 concerning them ; and thus, as science rose into 

 view, the spirit of commentation lost its sway. 

 And when men came to feel what it was to think 

 for themselves on subjects of science, they soon 

 rebelled against the right of others to impose 

 opinions upon them. When they threw off their 

 blind admiration for the ancients, they were dis- 

 posed to cast away also their passive obedience to 

 the ancient system of doctrines. When they were 

 no longer inspired by the spirit of commentation, 

 they were no longer submissive to the dogmatism 

 of the schools. When they began to feel that they 

 could discover truths, they felt also a persuasion 

 of a right and a growing will so to do. 



Thus the revived clearness of ideas, which made 

 its appearance at the revival of letters, brought on 

 a struggle with the authority, intellectual and civil, 

 of the established schools of philosophy. This clear- 

 ness of idea showed itself, in the first instance, 

 in Astronomy, and was embodied in the system of 

 Copernicus; but the contest did not come to a 

 crisis till a century later, in the time of Galileo 



