90 APHORISMS AND REFLECTIONS 



in that diligent, patient, loving study of all the 

 multitudinous aspects of Nature, the results of which 

 constitute exact knowledge, or Science. 



CCXXIII 



I find three, more or less contradictory, systems 

 of geological thought, each of which might fairly 

 enough claim these appellations, standing side by 

 side in Britain. I shall call one of them Cata- 

 strophism, another Uniformitarianism, the third 

 Evolutionism ; and I shall try briefly to sketch the 

 characters of each, that you may say whether the 

 classification is, or is not, exhaustive. 



By Catastrophism I mean any form of geological 

 speculation which, in order to account for the 

 phenomena of geology, supposes the operation of 

 forces different in their nature, or immeasurably 

 different in power, from those which we at present 

 see in action in the universe. 



The Mosaic cosmogony is, in this sense, cata- 

 strophic, because it assumes the operation of extra- 

 natural power. The doctrine of violent upheavals, 

 dc'bc'iclesy and cataclysms in general, is catastrophic, 

 so far as it assumes that these wrere brought about 

 by causes which have now no parallel. There was 

 a time when catastrophism might, pre-eminently, 

 have claimed the title of " British popular geology " ; 

 and assuredly it has yet many adherents, and reckons 

 among its supporters some of the most honoured 

 members of this Society. 



By Uniformitarianism I mean especially the 

 teaching of Hutton and of Lyell. 



That great though incomplete work, "The 

 Theory of the Earth," seems to me to be one of the 

 most remarkable contributions to geology which is 

 recorded in the annals of the science. So far as the 



