XXii THIRD REPORT — 1833. 



to the detriment of observation. To do this would be indeed 

 to render an ill service to science : but we conceive that our 

 purpose cannot so far be misunderstood. Without here at- 

 tempting any nice or technical distinctions between theory and 

 hypothesis, it may be sufficient to observe that all deductions 

 from theory for any other pupose than that of comparison with 

 observation are frivolous and useless exercises of ingenuity, so 

 far as the interests of physical science are concerned. Specu- 

 lators, if of active and inventive minds, will form theories 

 whether we wish it or no. These theories may be useful or 

 may be otherwise — we have examples of both results. If the 

 theories merely stimulate the examination of facts, and are 

 modified as and when the facts suggest modification, they may be 

 erroneous, but they will still be beneficial ; — they may die, but 

 they will not have lived in vain. If, on the other hand, our 

 theory be supposed to have a truth of a superior kind to the 

 facts ; to be certain independently of its exemplification in par- 

 ticular cases ; — if, when exceptions to our propositions occui', 

 instead of modifying the theory, we explain away the facts, — 

 our theory then becomes our tyrant, and all who work under 

 its bidding do the work of slaves, they themselves deriving no 

 benefit from the result of their labours. For the sake of ex- 

 ample we may point out the Geological Society as a body which, 

 labouring in the former spirit, has ennobled and eni-iched itself 

 by its exertions : if any body of men should employ themselves 

 in the way last described, they must soon expend the small 

 stock of a priori plausibility with which they must of course 

 begin the world. 



" To exemplify the distinction for a moment longer, let it be 

 recollected that we have at the present time two rival theories 

 of the history of the earth which prevail in the minds of geo- 

 logists ; — one, which asserts that the changes of which we trace 

 the evidence in the earth's materials have been produced by 

 causes such as are still acting at the surface ; another, which 

 considers that the elevation of mountain chains and the transi- 

 tion from the organized world of one formation to that of the 

 next, have been produced by events which, compared with the 

 present course of things, may be called catastrophes and con- 

 vulsions. Who does not see that all that those theories have 

 hitherto done, has been, to lead geologists to study more ex- 

 actly the laws of permanence and of change in the existing 

 organic and inorganic world, on the one hand; and on the 

 other, the relations of mountain chains to each other, and to 

 the phaenomena which their strata present ? And who doubts, 

 that, as the amount of the full evidence may finally be, (which 



