318 



SCIENCE 



[N. S. Vol. XLIX. No. 1266 



crease, but like tlie sacred beetles that also 

 have their sphere, we often roll our load with 

 clumsy slowness and humorous mishaps. 

 Nevertheless this sphere contains our intellec- 

 tual pabulum and is worth close scrutiny. 



In the first place it is to be observed that 

 like the moon the apparent size of this sphere 

 is highly variable. When we first view it in 

 the early student years it appears to have 

 moderate dimensions. Later it seems enor- 

 mous, but as the years go on it shrinks once 

 more, and I venture to think that in this last 

 phase our impressions correspond more nearly 

 to reality. 



An analysis of this experience may be 

 worth while. The mass before us is typified 

 by all that has been written plus the tradi- 

 tional wisdom which is handed down from 

 teacher to pupil. When the written records 

 are examined it becomes evident that the 

 greater portion of them are formed by an 

 enormous accumulation of evidence and argu- 

 ments for a relatively small number of im- 

 portant conclusions, and also for a multitude 

 of hypotheses which have perished by the way. 



Did you ever go into a well-stocked library 

 in which the books dealing with a given sub- 

 ject were arranged in their historical sequence, 

 and then ask yourself what could be said of 

 these — what was their larger meaning? It is 

 worth doing. One can, of course, dismiss the 

 greater number as out of date, a few only 

 have the power to remain alive. Tet all these 

 books, or nearly all, passed through a period 

 when they were consulted and esteemed. 



It is plain that most of our medical litera- 

 tvire, including that which represents the fun- 

 damental sciences, is concerned with the pre- 

 sentation of evidence and arguments for some 

 point of view. In the end the conclusions can 

 be stated in a few words. When these con- 

 elusions are established and made certain, 

 much of the literature developed by the way 

 becomes of historic interest only, to be 

 treasured and preserved of course, but re- 

 moved from the field of central vision. 



Thus when malaria was shown to be due to 

 pathogenic organisms — insectborne — the ante- 



cedent literatm-e concerned with other theories 

 of its etiology ceased to be intructive. 



One result of recognizing such a change is 

 to make the sphere of knowledge seem less 

 ponderous, yet it is never a small matter, and 

 there is always with us the question how we 

 can best handle this load of learning. In 

 many cases it is necessary to carry only a 

 skeleton outline of the existing knowledge, 

 yet one must be ever ready to follow a subject 

 into all of its details, when the occasion 

 demands. 



All this takes time and time presses cease- 

 lessly. Always we have with us tlie stubborn 

 fact that three score and ten years make a full 

 life, and that although the day may be short- 

 ened by legislative action, no hours can be 

 added. 



Joseph Leidy, the distinguished naturalist, 

 once said that he could carry some 20,000 

 names in mind, but if new ones were to be 

 acquired, some of the old ones must be for- 

 gotten. 



.This is a somewhat cryptic saying and 

 invites psychological analysis, but it also 

 serves to direct attention to the limitations 

 which beset even those exceptionally endowed. 

 Apparently we only carry those facts which 

 from tirae to time can be recalled. Neglect 

 them and they get lost : like foraging pigs they 

 must be called in now and then or they will 

 forget the way home. 



This sphere of learning which we have in 

 view is composed of facts that date from 

 many centuries. Some are surely very an- 

 cient, and strictly new ideas are hard to come 

 by. Our classical friends are fond of point- 

 ing out that many ideas which we parade to- 

 day were known to the Greek philosophers 

 2,000 years ago. Of course if persons make 

 a business of thinking, as did this group 

 among the ancients, they are bound to reach 

 a number of more or less logical conclusions, 

 though some of them may be quite contra- 

 dictory. It was not untU such rival conclu- 

 sions could be put to the experimental test 

 that it was possible to sift the true from the 

 false, and therefore our biological science 

 deals with no small number of ancient ideas 



