EDITORIAL.. 505 



mathematical expression for any organ, or even a single cell, although 

 formiilfe will continue to be useful for dealing now and then with 

 isolated details." 



But the aim of science does not stop at the accumulation of exact 

 records. It is directed to the attainment of accurate knowledge 

 develoiDed from these records. This is based upon a series of assump- 

 tions : " First, that there is absolute truth, which includes everything 

 we know or shall know; second, that we ourselves are included in 

 this absolute truth; third, that objective existence is real; fourth, 

 that our sensory perception of the objective is different from the 

 realit3\ These conceptions constitute our fundamental maxims, and 

 even when not definitely put in words they guide all sound scientific 

 research. . . . 



" The practical result of the four maxims has been that we further 

 assume that all errors are of individual human origin, and that there 

 are no objective errors. We make all the mistakes, nature makes 

 none. To render the pursuit of new knowledge successful, our basic 

 task is to eliminate error, or, in other words, to decide Avhen we have 

 sufficient proof. The elimination of error depends primarily upon 

 insight into the sources of error, which, since methods of all sorts 

 are employed, involves an intimate technical acquaintance with the 

 methods, with just what they can show, with what they can not show, 

 and with the misleading results they may produce. 



" In the laboratory training of a young scientific man, one chief 

 endeavor must always be to familiarize him with the good and the 

 bad of the special methods of his branch of science. Not until he 

 thoroughly understands the character and extent of both the prob- 

 able and the possible errors is he qualified to begin independent work. 

 His understanding must comprise the three sources of observational 

 error, namely, the variation of the phenomena, the imperfections of 

 the methods, and the inaccuracy of the observer. The personal equa- 

 tion always exists, although it can be quantitatively stated only in a 

 small minority of cases, 



" The history of science at large, the history of each branch of 

 science, and the personal experience of every active investigator all 

 equally demonstrate that the greatest source of error is in our inter- 

 pretations of the observations, and this difficulty depends, it seems 

 to me, more than upon any other one factor, upon our unconquerable 

 tendency to let our conclusions exceed the supporting power of the 

 evidence. Since generalization is the ultimate goal, we are too easily 

 inveigled into assuming probabilities to be certainties and into treat- 

 ing theories, and even hypotheses, as definite conclusions. Each gen- 

 eration of investigators in its turn spends much time killing off and 



