TWO ANTAGONIST DOCTRINES OF GEOLOGY. 675 



and their favourite maxim was, it is added, that 

 the time was not yet come for a General System of 

 Geology. This was a wise and philosophical temper, 

 and a due appreciation of their position. And even 

 now, their task is not yet finished; their mission 

 is not yet accomplished. They have still much to 

 do, in the way of collecting Facts ; and in entering 

 upon the exact estimation of Causes, they have only 

 just thrown open the door of a vast Labyrinth, 

 which it may employ many generations to traverse, 

 but which they must needs explore, before they can 

 penetrate to the Oracular Chamber of Truth. 



I REJOICE, on many accounts, to find myself arriv- 

 ing at the termination of the task which I have 

 attempted. One reason why I am glad to close my 

 history is, that in it I have been compelled, espe- 

 cially in the latter part of my labours, to speak as 

 a judge respecting eminent philosophers whom I 

 reverence as my Teachers in those very sciences on 

 which I have had to pronounce a judgment ; if, 

 indeed, even the appellation of Pupil be not too 

 presumptuous. But I doubt not that such men are 

 as full of candour and tolerance, as they are of 

 knowledge and thought. And if they deem, as I 

 did, that such a history of science ought to be 

 attempted, they will know that it was not only the 

 historian's privilege, but his duty, to estimate the 

 import and amount of the advances which he had 



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