302 Geological Society. 



this but to limit the riches of the kingdoms of nature by the poverty 

 of our own knowledge ; and to surrender ourselves to a mischie- 

 vous, but not uncommon philosophical scepticism, which makes us 

 deny the reality of what we have not seen, and doubt the truth of 

 what we do not perfectly comprehend ? 



Into the solution of the great problem of the heavenly bodies, 

 there enter only a few simple and unchangeable mechanical ele- 

 ments, and the conclusions are of a simplicity corresponding to the 

 simplicity of the premises. All the celestial movements return into 

 themselves; and even the most complex of the deviations pro- 

 duced by mutual perturbation, are confined within narrow limits, 

 and are completed in secular periods. The solution of this problem 

 is incontestably the greatest triumph of exact science. But with 

 what semblance of physical truth can we apply such mathematical 

 results as these to the great phenomena of geology where the com- 

 binations are mutable and indefinite where we have no vestige of 

 returning periods and where the fixed elements of force are either 

 unknown or imperfectly comprehended ? 



If all the complex groups of crystalline and stratified rocks; if, 

 in a word, all the material things existing on the surface of the 

 globe, be bound to each other by laws like those which govern 

 the movements of the heavenly bodies then every material combi- 

 nation we now see must re-appear with all its complicated relations 

 after the lapse of some long period of time. But would not such a 

 supposition be now regarded as the mere wantonness of hypothetical 

 extravagance ? And let it not be said, that it is only in the greater 

 combinations on the surface of the earth that we are to look for re- 

 turning cycles. Great and small have no meaning, except in reference 

 to us and our conceptions. The earth is an atom in comparison with 

 the visible creation; and all we now behold may be but as an atom in 

 comparison of that which is unseen ; and the meanest combinations 

 of material things submitted to our senses propagate their influence 

 through all space co-extensive with gravitation, and play their part 

 in keeping up the stability of the universe. 



To the supreme Intelligence, indeed, all the complex and mutable 

 combinations we behold, may be but the necessary results of some 

 simple law, regulating every material change, and involving within 

 itself the very complications, which we, in our ignorance, regard as 

 interruptions in the continuity of Nature's work. In contempla- 

 tions of this kind our understanding is lost among the stern doctrines 

 of philosophical necessity. But, as far as regards us and our facul- 

 ties, there is no such thing on earth as undeviating moral or phy- 

 sical necessity. For as, in morals, necessity is made, in part, at 

 least, subordinate to the freedom of human will ; so, in physics, the 

 continued action of immutable causes may and does co-exist with 

 mutable phenomena. 



The study of the great physical mutations on the surface of the 

 earth is the business of geology. But who can define the limits of 

 these mutations ? They have been drawn by the hand of nature, 

 and may be studied in the record of her works but they never 

 have been, and never will be fixed, by any guesses of our own, or by 



any 



