206 A CENTURY OF GEOLOGY. 



idea imderl^nng- oeologv and distinouishino- it from geography, viz, a 

 life history of the earth through all time. The elaim of geology to 

 a place in a scheme of classification is exactl_y the same as that of 

 astronomy. As astronomy is a held for the application of mathe- 

 matics, mechanics, physics, and, recently, chemistry, but is distin- 

 guished from them all by its characteristic fundamental idea of illimit- 

 al)le space, so geology is a field for the application of all other lower 

 sciences, but is distinguished from them all b}" her characteristic, 

 fundamental idea of illimitable time. As all other sciences are terres- 

 trial, but astronomy alone celestial, so all other sciences ])elong to the 

 present — the "'now"" — but geology alone belongs to the illimitable 

 past. The fundamental idea of the one is infinite space, of the other 

 infinite, in sense of inconceivable, time. All other sciences, including 

 astronomy, are but a flash-light view of Nature. Geology alone is a 

 view of Nature in continuous movement — a life history — an evolution 

 of Nature. This mode of thought began to dawn only in the closing 

 years of the last and the opening years of the present century. It 

 seems to have been first clearly conceived by the mind of Hutton in 

 the last part of the eighteenth century. 



2. Inductive method applied. — When the true idea underlying geol- 

 ogy was clearly conceived, and geolog}" thus distinctl}' separated from 

 other departments of science, geolog}' may ])e said to have been born. 

 But it was still in helpless infanc}", its growth irregular, and even its 

 continuous life uncertain, because a solid basis of inductive method 

 was not yet laid. That basis was laid mainly h}- Hutton in 1795^ 

 and still more clearly h\ Charles Lyell in 1830, in the principle that 

 the stud}' of causes now in operation is the onh^ true foundation of 

 geology. 



Geological changes, of course, belong to the irrevocable past, and are 

 therefore hopelessly removed from direct observation. Their causes 

 and process must be reconstructed by the skillful use of the scientific 

 imagination. Until Lyell, more or less probable hypotheses seemed 

 all that was possible. What a field was here for the conflict of oppo- 

 site extreme views! But Lj^ell showed that " causes now in operation " 

 are producing similar efl'ects under our eyes, if we will onl}' observe. 

 From that moment geologj^ became a tvxAj inductive science and its 

 indefinite progress assured. 



These two events, then, viz, the conception of geology as a distinct 

 science and the introduction of a true scientific method, are the great- 

 est epochs in the history of geological science. Some dim adumbra- 

 tions of these appear before this century, especially the former in the 

 mind of Bufl'on, and the latter somewhat full}- in the mind of Hutton, 

 but they were not generally accepted and had not become working 

 principles until the beginning and even some time after the beginning 



1 Hutton's Theory of the Earth. 



