AN AUTOBIOGRAPHICAL SKETCH. 279 



moscope. He had merely neglected to put the ques- 

 tion, To what optical image do the rays belong, which 

 come from the illuminated eye ? For the purpose he 

 then had in view it was not necessary to propound this 

 question. If he had put it, he was quite the man to 

 answer it as quickly as I could, and the plan of the 

 ophthalmoscope would have been given. I turned the 

 problem about in various ways, to see how I could best 

 explain it to my hearers, and I thereby hit upon the 

 question I have mentioned. I knew well, from my 

 medical studies, the difficulties which oculists had 

 about the conditions then comprised under the name 

 of Amaurosis, and I at once set about constructing the 

 instrument by means of spectacle glasses and the glass 

 used for microscope purposes. The instrument was at 

 first difficult to use, and without an assured theoretical 

 conviction that it must work, I might, perhaps, not 

 have persevered. But in about a week I had the great 

 joy of being the first who saw clearly before him a 

 living human retina. 



The construction of the ophthalmoscope had a very 

 decisive influence on my position in the eyes of the 

 world. From this time forward I met with the most 

 willing recognition and readiness to meet my wishes on 

 the part of the authorities and of my colleagues, so that 

 for the future I was able to pursue far more freely the 

 secret impulses of my desire for knowledge. I must, 



