1 8 LAY SERMONS, ADDRESSES, AND REVIEWS. h. 



ceptcd it, reason has no further duty. There are many 

 excellent persons who yet hold by these principles, and 

 it is not my present business, or intention, to discuss 

 their views. All I wish to bring clearly before your 

 minds is the unquestionable fact, that the improvement 

 of natural knowledge is effected by methods which 

 directly give the lie to all these convictions, and assume 

 the exact reverse of each to be true. 



The improver of natural knowledge absolutely refuses 

 to acknowledge authority, as such. For him, scepticism 

 is the highest of duties ; blind faith the one unpardon- 

 able sin. And it cannot be otherwise, for every great 

 advance in natural knowledge has involved the absolute 

 rejection of authority, the cherishing of the keenest 

 scepticism, the annihilation of the spirit of blind faith ; 

 and the most ardent votary of science holds his firmest 

 convictions, not because the men he most venerates 

 hold them ; not because their verity is testified by 

 portents and wonders ; but because his experience teaches 

 him that whenever he chooses to bring these convictions 

 into contact with their primary source, Nature — when- 

 ever he thinks fit to test them by appealing to experiment 

 and to observation — Nature will confirm them. The 

 man of science has learned to believe in justification, 

 not by faith, but by verification. 



Thus, without for a moment pretending to despise 

 the practical results of the improvement of natural 

 knowledge, and its beneficial influence on material civili- 

 zation, it must, I think, be admitted that the great 

 ideas, some of which I have indicated, and the ethical 

 spirit which I have endeavoured to sketch, in the few 

 moments which remained at my disposal, constitute the 

 real and permanent significance of natural knowledge. 



If these ideas be destined, as I believe they are, to 

 be more and more firmly established as the world grows 



