46 POPULAR LECTURES AND ADDRESSES. 



of -i perpetual violation of those laws of action 

 between matter and matter which we are allowed 

 to investigate here at the surface of the earth, 

 in our laboratories and mechanical workshops. 

 The geologists who have uncompromisingly 

 adopted Playfair's maxim have reasoned as if 

 the sun were so created. I believe it was 

 altogether thoughtlessness that led them ever to 

 put themselves 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, I 

 think we may even consider them as having gone 

 too far in assuming that we must consider present 

 laws a very small part of which we have been 

 able to observe as sufficient samples of the 

 perennial laws regulating the whole universe in 

 all time. But I believe it has been altogether an 

 oversight by which they have been led to neglect 

 so greatly the fact of the sun's heat and light 



22. The mutual actions and motions of the 

 heavenly bodies have been regarded as if light had 

 been seen and heat felt without any evolution of 



