EARLY LIFE AND STUDIES. 253 



neither tranquillity nor relaxation, nor the flattering 

 attentions of his equals in age and station, nor public 

 games nor banquets would delight; who would regard 

 nothing in life as desirable which was not united with 

 dignity and virtue ; such a man I regard as being, in 

 my judgment, furnished and adorned with some special 

 gifts of the gods.' 



His medical studies were pursued with the thorough- 

 ness which marked everything Young took in hand. 

 He was an assiduous attendant at the best lectures. 

 His delight in optics naturally drew him to investigate 

 the anatomical structure of the eye. In regard to this 

 structure it will be remembered that in front is the 

 cornea, holding behind it the aqueous humour ; then 

 comes the iris, surrounding the aperture called the 

 pupil, at the back of which we have the crystalline 

 lens. Behind this, again, is the vitreous humour, which 

 constitutes the great mass of the eye. Thus, optically 

 considered, the eye is a compound lens of great com- 

 plexity and beauty. Behind the vitreous humour is 

 spread the screen of the retina, woven of fine nerve- 

 fibres. On this screen, when any object looked at is 

 distinctly seen, a sharply-defined image of the object 

 is formed. Definition of the image is necessary to the 

 distinctness of the vision. Were the optical arrange- 

 ments of the eye rigid, distinct vision would be pos- 

 sible only at one definite distance. But the eye can 

 see distinctly at different distances. It has what the 

 Germans call an Accommodationsvermogen a power 

 of adjustment which liberates it from the thrall of 

 rigidity. By what mechanical arrangement is the eye 

 enabled to adjust itself both for near and distant 

 objects? Young replied, 'By the alteration of the 

 curvature of the crystalline lens.' Hig memoir on this 

 subject was considered ,so meritorious, that it was 



