PROGRESS OP HUMAN KNOWLEDGE. 3 



human knowledge. Such records from time to time, 

 even if imperfect, have their use in denoting the 

 several stages of advancement marked not only by new 

 facts but also by new methods of enquiry. The latter 

 is the point I would chiefly keep in view in what I am 

 now writing. Laplace has said, and truly, that the 

 methods which have led to discovery are often not less 

 useful to science than the discoveries themselves. 

 And nothing so well deserves note in the attainments 

 of the present age as the various new resources, 

 mental and material, which have been brought to bear 

 on the advancement of human knowledge of the 

 physical sciences more especially, but even of those en- 

 quiries into invisible things, which have perplexed men 

 from one age to another. The stricter demand for 

 proof, as applied to the material world, has borne 

 some fruit even in this obscure region of speculative 

 thought. 



What I am about to write on this subject will have 

 little novelty for scientific men, or those who have re- 

 flected upon it, but may serve to give others out of 

 this pale some general ideas of the actual attainments 

 of our time, and some presage of what lies beyond it 

 in the future. 



The better determination of /what is solved and 

 what unresolved, and the same discrimination applied 

 to the higher question of what things are resolvable and 

 what irresolvable by human research, are points which 

 may first be noted as characteristic of the science of 

 our time. Truth and certainty are more clearly defined 

 as the objects sought for under the conditions just 



B 2 



