THEORIES OF TEMPEIiATUEE CHANGES. 263 



Again, we may cite the opinion of another scientist, whose right to speak 

 with authority on a qnestion of the kind now before us will be denied by 

 none. Sir William Thomson has stated his views in regard to the possibility 

 of admitting that the sun may go on radiating heat without diminution, for an 

 indefinite period, in the following language : " Life on this earth would not 

 be possible without the sun, that is, life under the present conditions — life 

 such as we know and can reason about. When Playfoir spoke of the plane- 

 tar}' bodies as being perpetual in tlieir motion, did it not occur to him to 

 ask. What about the sun's heat? Is the sun a miraculous body ordered to 

 give out heat and shine forever? Perhaps the sun was so created. He 

 would be a rash man who would say it was not — all things are possible to 

 Creative Power. But we know, also, that Creative Power has created in our 

 minds a wish to investigate and a capacity for investigating ; and there is 

 nothing too rash, there is nothing audacious in questioning human assump- 

 tions rea;ardint>- Creative Power. Have we reason to believe Creative Power 

 did order the sun to go on, and shine, and give out heat forever? Are we to 

 suppose that the sun is a perpetual miracle ? I use the word miruck in the 

 sense of a perpetual violation of those laws of action between matter and 

 matter which we are allowed to investigate liere at the surface of the earth, 

 in our laboi-atories and mechanical woi'kshops. The geologists who have 

 adopted Playfair's maxim have reasoned as if the sun were so created. I 

 believe it Avas altogether thoughtlessness that led them ever to put them- 

 selves in that position ; because these same geologists are very strenuous in 

 insisting that we must consider the laws observable in the present state of 

 things as perennial laws But I believe it has been altogether an over- 

 sight by which they have been led to neglect so greatly the fact of the sun's 

 light and heat."* 



In another paper on the same subject, Sir W. Thomson expresses himself 

 still more forcibly. He says : " Consider next the evidence with which geo- 

 logical investigation teems of warmer climate all over the earth from equator 



to pole in the more ancient geological periods The one hypothesis [to 



account lor the warmer climate of ancient times] of all hitherto suggested 

 that has received no favor from any professed geologist is that of a warmer 

 sun — the one hypothesis that is rendered almost infinitely probable by 

 independent physical evidence and mathematical calculation.'"! 



* TraiLsactioiis of the Geulogical Society of Glasgow, Vol. III. pp. 16-17. 

 + 1. c, Vol. v. p. 250. 



