Apeil 4, 1919] 



SCIENCE 



319 



and the contribution of the modem workers is 

 the selection of those which can survive the 

 trial. As the expression goes : we test the hy- 

 iwthesis. Ideas which can survive the blows 

 and buffets of time have a certain prestige 

 and digrnity which is to be reckoned to their 

 credit, while the nimiber born to perish, those 

 that appear but once, are as the eggs of a fish. 

 Moreover, it is most important for us in 

 weighing the worth of ideas to know some- 

 thing of their history — I might almost say 

 their ancestry — and not to confuse the un- 

 baked results of the hour with those that have 

 an ancient lineage. If we realize then the 

 persistent character of all first-class problems, 

 it ceases to be a wonder that when the results 

 of an investigation are followed back into the 

 literature, some of them may be found fore- 

 shadowed there or even definitely formulated, 

 sometimes on good grounds, sometimes on bad. 



Of course there are critical points in the 

 advancement of knowledge which, when 

 passed, make possible conclusions that are 

 plainly novel and could not have been reached 

 before. The aspect of medicine changed after 

 Harvey discovered the circulation of the blood. 

 The heat of the body appeared in a new light 

 after Lavoisier developed the theory of oxida- 

 tion. Galvani's observations on the nerves 

 and muscles of frogs gave a new idea of the 

 nervous impulse, and Johannes Miiller's doc- 

 trine of the specific energies of nerves revolu- 

 tionized our notions of the sense organs. 

 Infectious disease suddenly became intelligible 

 in tlie light of the work of Pasteur, and the 

 doctrine of internal secretions and the chem- 

 ical messengers, taking its departure from the 

 observations of Brown-Sequard, shod a world 

 of light on the control of body functions and 

 relieved the nervous system from responsi- 

 bilities which were proving too heavy for it. 



If then we come back to our sphere of 

 knowledge and endeavor to see in what man- 

 ner it is compounded, we find in it ideas which 

 repeat themselves at every revolution. We 

 find great masses of information which, be- 

 cause they have sen'ed their purpose in estab- 

 lishing points of view, now have mainly an 

 historical interest, and overlying all, most con- 



spicuous and best known is the newer knowl- 

 edge, the kind you have just labored to ac- 

 quire, composed of these elements in part but 

 in larger part consisting of detailed evidence, 

 valuable for the newer points of view. 



It requires some skill to manipulate this 

 mass of information without being smothered 

 by the dust of it, but handbooks, summaries, 

 digests, reviews and journals deal with it in 

 such a way that one can get their bearings 

 with a comparatively small expenditure of 

 time. 



There still remains the question how this 

 information by which we live should be re- 

 garded. There have been communities and 

 times when medical learning was handled al- 

 most as a trade secret, indeed the Hippocratic 

 oath suggests that this idea was an ancient 

 one. It was as though the possessor had ac- 

 quired a fixed and rigid formula for making a 

 peculiarly good article useful to the public, 

 but the production of which should be pro- 

 tected. This attitude has been abandoned 

 happily, save in the most backward communi- 

 ties and among the least intelligent prac- 

 titioners; The modem and the progressive 

 view is quite different. It is in harmony with 

 the response of John Hunter the great com- 

 parative anatomist, when some one quoted to 

 him a statement which he had made a year 

 before. " Sir," he replied, " I am not to be 

 held by my statements of a year ago." He 

 had progressed in the interval and he had ac- 

 cordingly changed his opinion. The knowl- 

 edge which has been presented to you, and to 

 which you have added by your own industry, 

 is to be sure the best available at the moment, 

 but that is the most that can be said of 

 medicine and the most that can be said of any 

 science. If we believed otherwise, if for a 

 moment we thought of it as fixed and final, 

 those of us at least who work in laboratories 

 would promptly go into the chrysalis stage and 

 somnolently wait for immortality. That how- 

 ever is not done. To-day the best use pos- 

 sible is made of such information as we have 

 been able to gather, but with the confident 

 expectation that to-morrow will bring new 

 knowledge. Look at the extension of our 



