434 A SHORT HISTORY OF SCIENCE 



might discover the laws which regulated the movements of distant 

 planets. 



The establishment, from time to time, of numerous points of identi- 

 fication, drew at length from geologists a reluctant admission, that 

 there was more correspondence between the physical constitution 

 of the globe, and more uniformity in the laws regulating the changes 

 of its surface, from the most remote eras to the present, than they at 

 first imagined. If, in this state of the science, they still despaired or 

 reconciling every class of geological phenomena to the operations of 

 ordinary causes, even by straining analogy to the utmost limits of 

 credibility, we might have expected, that the balance of probability 

 at least would now have been presumed to incline towards the identity 

 of the causes. But, after repeated experience of the failure of attempts 

 to speculate on different classes of geological phenomena, as belong- 

 ing to a distinct order of things, each new sect persevered systematic- 

 ally in the principles adopted by their predecessors. They invariably 

 began, as each new problem presented itself, whether relating to the 

 animate or inanimate world, to assume in their theories, that the 

 economy of nature was formerly governed by rules quite independent 

 of those now established. Whether they endeavoured to account 

 for the origin of certain igneous rocks, or to explain the forces which 

 elevated hills or excavated valleys, or the causes which led to the 

 extinction of certain races of animals, they first presupposed an orig- 

 inal and dissimilar order of nature ; and when at length they approxi- 

 mated, or entirely came round to an opposite opinion, it was always 

 with the feeling, that they conceded what they were justified d priori 

 in deeming improbable. In a word, the same men who, as natural 

 philosophers, would have been greatly surprised to find any deviation 

 from the usual course of Nature in their own time, were equally sur- 

 prised, as geologists, not to find such deviations at every period of 

 the past. 



The Huttonians were conscious that no check could be given to 

 the utmost license of conjecture in speculating on the causes of geo- 

 logical phenomena, unless we can assume invariable constancy in 

 the order of Nature. But when they asserted this uniformity with- 

 out any limitation as to time, they were considered, by the majority 

 of their contemporaries, to have been carried too far, especially as 

 they applied the same principle to the laws of the organic, as well as 

 of the inanimate world. 



