i 9 2o] Final Test of Truth 



limitations. The enormously distant and the extremely 

 small elude precise observations, star and electron 

 baffle alike; the bulk of the Universe is beyond our 

 definite seeing. "Time is as long as space is wide," 

 and no one can conceive a limit to either. 



The sciences concerned with life deal also with the 

 elements of matter and force, but in highly varying 

 relations. In any biological problem, conditions due 

 to the relative position and relation of atoms and 

 molecules, of cells and tissues, of organisms and 

 environment, are visibly varied almost to infinity; 

 data of one sort or another everywhere abound, but 

 the more we have, the more we see we need. Untested 

 problems crowd on every solution. In biology, 

 therefore, to a degree greater than in the more exact 

 sciences, we cannot know what we know or what 

 we do not know with completeness or ultimate 

 precision. 



The only final test of a supposed fact is found in 

 our ability to prove it by trusting our lives to it, or 

 to the method by which it is gained. Simply to 

 demonstrate that a proposition will "work" -that 

 is, "muddle along" after a fashion is not enough; 

 in all its parts it must stand a supreme test, that of 

 "livableness." Such a direct and conclusive proof, 

 however, is not available in all life's complex and 

 immediately pressing situations. The next resource 

 is to test the method behind the conclusion. The 

 aggregate of knowledge, so tested, constitutes Science, 

 which then becomes the guide to conduct, though 

 never infallible because never complete. In default 

 of personal experimental knowledge as to matters of 

 fact or ideals of conduct, we make the best we can 

 of the conclusions of others, trusting to the strength 



