394 



THE POPULAR SCIENCE MONTHLY. 



led to review tlie labors of other searchers from this standpoint, 

 because I had first learned, out of j)ersonal experience, that the 

 most painstaking care was no guarantee of final accuracy ; that to 

 labor in the search for a truth with such endless pains as a man 

 might bestow if his own salvation were in question did not neces- 

 sarily bring the truth ; and because, seeking to see whether this 

 were the lot of other and greater men, I have found that it was, 

 and that, though no one was altogether forsaken of the Truth he 

 sought (or, on the whole review of his life as a seeker, but might 

 believe he had advanced her cause), yet there was no criterion by 

 which it could be told at the time whether, when after long wait- 

 ing there came in view what seemed once more her beautiful face, 

 it might not prove, after all, the mockery of error ; and probably 

 the appeal might be made to the experience of many investigators 

 here with the question, " Is it not so ? " 



What then ? Shall we admit that truth is only to be surely 

 found under the guidance of an infallible church ? If there be 

 such a church, yes ! Let us, however, remember that the church 

 of science is not such a one, and be ready to face all the conse- 

 quences of the knowledge that her truths are put forward by her 

 as provisional only, and that her most faithful children are wel- 

 come to disprove them. What then, again ? Shall we say that 

 the knowledge of truth is not advancing ? It is advancing, and 

 never so fast as to-day ; but the steps of its advance are set on 

 past errors, and the new truths become such stepping-stones in 

 turn. 



To say that what are truths to one generation are errors to the 

 next, or that truth and error are but different aspects of the same 

 thing to our poor human nature, may be to utter truisms ; but 

 truisms which one has verified for one's self out of a personal ex- 

 perience are apt to have a special value to the owner ; and these 

 lead, at any rate, to the natural question, " Where is then the evi- 

 dence that we are advancing in reality, and not in our own imagi- 

 nation ? " 



There are many here who will no doubt heartily subscribe to 

 the belief that there is no absolute criterion of truth for the indi- 

 vidual, and admit that there is no positive guarantee that we, with 

 this whole generation of scientific men, may not, like our pre- 

 decessors, at times go the wrong way in a body, yet who believe 

 as certainly that science as a whole, and this branch of it in par- 

 ticular, is advancing with hitherto unknown rapidity. In asking 

 to be included in this number, let me add that to me the criterion 

 of this advance is not in any ratiocination, not in any a priori 

 truth, still less in the dictum of any authority, but in the un- 

 doubted observation that our doctrine of radiant energy is reach- 

 ing out over nature in every direction, and proving itself by the 



