PROFESSOR AT KONIGSBERG 73 



riddles, which are probably only understood by a handful 

 of one's hearers/ 



His father, to whom he had sent his lecture on February 27, 

 was by no means of this opinion, and writes on April 19 to 

 du Bois-Reymond : 



1 Dear Doctor, heartiest thanks for the copy of your interest- 

 ing lecture to the scientific society. I rejoiced in the clearness 

 of your style, which enables even the uninitiated to glance 

 into the secrets of your science, and by its wit and poetic 

 taste redeems it from its usual dryness. It is admirable 

 in you amid your heavy labours thus to find time to refresh 

 yourself with the poets, and to round the realism of your 

 nature-studies with art and poetry. I wish my son had some- 

 thing of your spirit: he is so little able to escape from his 

 scientific rigidity of expression, even in an essay read before 

 a Society in Ko"nigsberg, that I am filled with respect for an 

 audience that could understand and thank him for it. I confess 

 that when I read it much remained very obscure to me/ 



While Helmholtz was thus engaged in fundamental researches 

 which had the common aim of building up a mechanical con- 

 ception of the universe (in the best sense), he lighted casually, 

 and as the fruit of his lectures at the end of 1850, upon his 

 discovery of the ophthalmoscope, which ' revealed a new 

 world 1 to the ophthalmologists, and which, with the doctrine 

 oi the Conservation of Energy, did most to establish and extend 

 his reputation. 'The excellent discipline every University 

 teacher is subject to, in being obliged each year to treat the 

 whole of his subject so as to convince and satisfy the best 

 of his students/ resulted on his own avowal in this splendid 

 harvest. 



After communicating his invention to the Physical Society 

 in Berlin, on December 6, he wrote on December 17, 1850, to 

 his father: 



' In regard to time- measurements I have at present no new 

 results, but have devoted myself to the construction of fresh 

 apparatus and necessary preliminaries. But I have made a 

 discovery during my lectures on the Physiology of the Sense- 

 organs, which may be of the utmost importance in ophthalmo- 

 logy. It was so obvious, requiring, moreover, no knowledge 

 beyond the optics I learned at the Gymnasium, that it seems 



