Ch. I.] METHODS OF THEORIZING IN GEOLOGY. 3 



and to blunt the keen edge of curiosity, than this assumption 

 of the discordance between the former and the existing causes 

 of change. It produced a state of mind unfavourable in the 

 highest conceivable degree to the candid reception of the evi- 

 dence of those minute,, but incessant mutations, which every 

 part of the earth's surface is undergoing, and by which the 

 condition of its living inhabitants is continually made to vary. 

 The student, instead of being encouraged with the hope of 

 interpreting the enigmas presented to him in the earth's struc- 

 ture, instead of being prompted to undertake laborious 

 inquiries into the natural history of the organic world, and 

 the complicated effects of the igneous and aqueous causes now 

 in operation, was taught to despond from the first. Geology, it 

 was affirmed, could never rise to the rank of an exact science, 

 the greater number of phenomena must for ever remain inex- 

 plicable, or only be partially elucidated by ingenious conjec- 

 tures. Even the mystery which invested the subject was said to 

 constitute one of its principal charms, affording, as it did, full 

 scope to the fancy to indulge in a boundless field of speculation. 



The course directly opposed to these theoretical views con- 

 sists in an earnest and patient endeavour to reconcile the former 

 indications of change with the evidence of gradual mutations 

 now in progress ; restricting us, in the first instance, to known 

 causes, and then speculating on those which may be in activity 

 in regions inaccessible to us. It seeks an interpretation of 

 geological monuments by comparing the changes of which they 

 give evidence with the vicissitudes now in progress, or which 

 may be in progress. 



We shall give a few examples in illustration of the practical 

 results already derived from the two distinct methods of theo- 

 rizing, for we have now the advantage of being enabled to 

 judge by experience of their respective merits, and by the rela- 

 tive value of the fruits which they have produced. 



In our historical sketch of the progress of geology, the reader 

 has seen that a controversy was maintained for more than a 

 century, respecting the origin of fossil shells and bones- were 



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