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ClL V.] 



ANCIENT AND MODERN CAUSES. 



105 



presumed 



close analogy of the ancient and modern causes. But, after 

 repeated experience of the failure of attempts to speculate 

 on geological monuments, as belonging to a distinct order of 

 things, new sects continued to persevere in the principles 



They still began, as each 

 tether relating to the animate 



adopted by their predecessors. 



or 



assume an 



original 



and dissimilar 

 order of nature ; and when at length they approximated, or 



came 



al 



ways 



with the feeling, that they were conceding what they had 



>robable. In a word, 



deeminp 4 im 



same 



most incredulous respecting any extraordinary deviations 

 from the known course of nature, if reported to have hap- 

 pened in their own time, were equally disposed, as geologists, 

 to expect the proofs of such deviations at every period of 



the past. 



I shall proceed in the following chapters to enumerate 



some of the principal difficulties still opposed to the theory 



of the uniform nature and energy of the causes which have 



worked successive changes in the crust of the earth, and in 



the condition of its living inhabitants. The discussion of so 



important a question on the present occasion may appear 



premature, but it is one which naturally arises out of a 



review of the former history of the science. It is, of course, 



impossible to enter into such speculative topics, without 



occasionally carrying the novice beyond his depth, and 



appealing to facts and conclusions with which he will be 



unacquainted, until he has studied some elementary work on 



geology, but it may be useful to excite his curiosity, and 



lead him to study such works by calling his attention at 



once to some of the principal points of controversy.*" 



* In the earlier editions of this work, the crust of the earth. This I after- 



a fourth book was added on Geology wards (in 1838) expanded into a sepa- 



Proper, or Systematic Geology, con- rate publication called the Elements or 



taining an account of the former changes Manual of Geology, of which a sixth 



of the animate and inanimate creation, edition appeared, January 1865. 

 brought to light by an examination of 



