422 THE SCIENTIFIC MONTHLY 



he conceived the desire to show it to his students, he was the first to see 

 the living human retina. 



While following the invention of the ophthalmoscope, Helmholtz 

 was occupied for some years with physiological optics, it can not be 

 said that it "set" his career as it might have done with another man, as 

 for instance his invention of the stethoscope did with Laennec. The 

 latter putting a paper cylinder to a consumptive girl's chest discovered 

 that through it he could hear the sounds of moisture vastly better than 

 by direct application of the ear. Here was a method, and the young 

 clinician devoted the rest of his own all too short consumptive's life 

 to diseases of the chest. Helmholtz turned the so called practical ap- 

 plication of his ophthalmoscope over to the clinicians and busied him- 

 self with the discovery of new facts and explanation of old, quite re- 

 gardless of their direct application to the ills of man. The physics was 

 the more attractive field than the pathology, and to the end of his life 

 he gravitated more and more from the latter toward the former, until 

 the boy of twenty-eight, who started out as a professor of physiology 

 and pathology at Konigsberg, became at fifty the dominating figure of 

 the time in physical science as professor of physics in Berlin. While he 

 was one of the masters of medicine, his contributions were toward 

 theory and not practise, his name being associated in the science chiefly 

 with the explanation of vision and hearing and the theory of color 

 and tone. That immeasurable practical use of his discoveries is being 

 made goes without saying. But it is indeed a fortunate thing for man- 

 kind that the superb intellect of Helmholtz was not turned into the 

 superficial channels of practical usage but was left free to explore the 

 unknown depths below. 



In later years his trend of thought took him more into the field of 

 dynamics and electro-dynamics, bringing him back to the direct course 

 on which he started forty years before with his immortal essay on the 

 Conservation of Energy. His intellectual goal was never a democratic 

 one. He felt it his duty as a disciple of science to ascertain truth for 

 its own sake, and no man more strongly decried the pursuit of science 

 merely for the practical results. His clear exposition of the principles 

 of the transformation of energy furnishes the index of his character, 

 and, whatever the practical applications of the principles thus enunci- 

 ated may be, we can not avoid the impression of something essentially 

 aristocratic in a young man of twenty-six killing for all time with one 

 blow, the idea of a machine for perpetual motion. 



Obviously the points of view of Pasteur and Helmholtz were fairly 

 far apart. This does not mean that the one was consistently demo- 

 cratic and the other at all times aristocratic in the sense defined above, 

 throughout their long lives of scientific research. Many times the 

 roles were reversed. Helmholtz contributed a practical remedy for 



