GENERAL OBSERVATIONS: ON REPETITION OF EXPERIMENTS 641 



it, and no one else need consider the problem farther, especially 

 if that someone is a person of reputation. No supposition could 

 be wider of the mark! Some reputations are founded on a rock, 

 others are mere bubbles. Moreover, nature hides from us very 

 securely her secret things, and the chances of going astray in 

 their interpretation are many. The young scientific man, filled 

 with his intellectual pride and knowing very little really, either 

 about the complexities of nature or the history of science, which 

 for the most part is the story of one long series of blunderings 

 (toward the light, however, not into deeper darkness), is apt to 

 judge the mistakes of his fellows and of older men harshly; the 

 experienced honest man, on the contrary, knows that to err is 

 human and judges all honest work leniently, since he knows that 

 even the best work is certain to contain some erroneous observa- 

 tions, or some errors of interpretation. 



Remember this, therefore, as a fundamental doctrine in 

 science: Nothing is too sacred to investigate, and nothing can be 

 regarded as indubitably established until various careful observers 

 and experimenters have arrived independently at the same conclu- 

 sion. Copy this out and stick it up where you can see it every 

 day! If the second man over a subject finds the first man correct 

 in all essential observations and interpretations, the more credit 

 to the former. The second man will, nevertheless, usually be 

 able to extend the first man's observations somewhat and should 

 leave the field clearer than he found it and in any event his ob- 

 servations will be useful, as confirmation. Unfortunately, often, 

 as the history of science shows, the second man over a subject is 

 only a bumptious fool, and, when he has finished, the subject 

 is covered with a cloud of uncertainty, until some third man, of 

 greater ability, goes once more methodically over the entire 

 field, blows away the dust, and again sets matters in their true 

 light. If you repeat a man's experiments, try to be at least as 

 painstaking and circumspect as he was, unless you wish to be 

 intellectually pilloried for the contempt of oncoming genera- 

 tions. Never think it a waste of time or a work of superer- 

 ogation to repeat the experiments of another person. Do not 

 call it '' duplication of work." It is not that, because no two 

 individuals ever bring to a problem just the same sort of train- 



