So6 POPULAR SCIENCE MONTHLY. 



Considerations like these, unless I have compressed them beyond 

 the limits of intelligibility, do undoubtedly suggest a certain inevitable 

 incoherence in any general scheme of thought which is built out of 

 materials provided by natural science alone. Extend the boundaries 

 of knowledge as you may; draw how you will the picture of the uni- 

 verse; reduce its infinite variety to the modes of a single space-filling 

 ether ; retrace its history to the birth of existing atoms ; show how under 

 the pressure of gravitation they became concentrated into nebula?, into 

 suns, and all the host of heaven ; how, at least in one small planet, they 

 combined to form organic compounds; how organic compounds became 

 living things ; how living things, developing along many different lines, 

 gave birth at last to one superior race; how from this race arose, after 

 many ages, a learned handful, who looked round on the world which 

 thus blindly brought them into being, and judged it, and knew it for 

 what it was: perforin (I say) all this, and though you may indeed have 

 attained to science, in nowise will you have attained to a self-sufficing 

 system of beliefs. One thing at least will remain, of which this long- 

 drawn sequence of causes and effects gives no satisfying explanation; 

 and that is knowledge itself. Natural science must ever regard knowl- 

 edge as the product of irrational conditions, for in the last resort it 

 knows no others. It must always regard knowledge as rational, or else 

 science itself disappears. In addition, therefore, to the difficulty of 

 extracting from experience beliefs which experience contradicts, we are 

 confronted with the difficulty of harmonizing the pedigree of our be- 

 liefs with their title to authority. The more successful we are in 

 explaining their origin, the more doubt we cast on their validity. The 

 more imposing seems the scheme of what we know, the more difficult it 

 is to discover by what ultimate criteria we claim to know it. 



Here, however, we touch the frontier beyond which physical science 

 possesses no jurisdiction. If the obscure and difficult region which lies 

 beyond is to be surveyed and made accessible, philosophy, not science, 

 must undertake the task. It is no business of this society. We meet 

 here to promote the cause of knowledge in one of its great divisions; 

 we shall not help it by confusing the limits which usefully separate 

 one division from another. It may perhaps be thought that I have 

 disregarded my own precept; that I have wilfully overstepped the am- 

 ple bounds within which the searchers into nature carry on their labors. 

 If it be so, I can only beg your forgiveness. My first desire has been 

 to rouse in those, who, like myself, are no specialists in physics, the 

 same absorbing interest which I feel in what is surely the most far- 

 reaching speculation about the physical universe which has ever claimed 

 experimental support; and if in so doing I have been tempted to hint 

 my own personal opinion, that as natural science grows it leans more, 

 not less, upon an idealistic interpretation of the universe, even those 

 who least agree may perhaps be prepared to pardon. 



