BOOK XI. Liv. 146-LV. 149 



blinds the eyes by withdrawing the vision inwai'd, and 

 why when the mind is clouded during an attack of 

 epilepsy the eyes though open discern nothing. 

 Moreover hares sleep with the eyes wide open, and 

 so do many human beings while in the condition 

 which the Greeks term ' corybantic.'" 



Nature has constructed them with thin and multiple Physioiogy 

 niembranes, and with outside wrappers that are callous '^ ^^' 

 against cold and heat, whicli she repeatedly cleanses 

 with moisture from the tear-glands, and she has made 

 the eyes shppery against objects that encounter them, 

 and mobile. I^V. The horny skin in the centre of the 

 eye nature has furnished with the pupil as a window, 

 the narrow opening of which does not allow the gaze to 

 roam uncertain, but so to speak canalizes its direetion, 

 and easily averts objects that encounter it on the 

 way ; the pupil is surrounded with circles which with 

 some people are coloured black, with others grey and 

 with others blue, so that the hght from the surroun- 

 ding radiance both may be received in a suitable 

 blend and having its reflexion moderated may not be 

 jarring; and the efficacy of the mirror is made so 

 perfect by these means that the small pupil can 

 reflect the entire image of a human being. This . 

 is the reason why commonly birds when released 

 from men's hands go tirst of all for their eyes, be- 

 cause they see their own hkeness reflected in them 

 and try to reach as it were a desired object that is 

 akin to themselves. Beasts of burden only experience 

 diseases at certain phases of the moon. Man alone Cure of 

 is cm*ed of bhndness by the emission of fluid from the "' "*"' 

 eye. Many have had their sight restored after 20 

 years of bhndness ; some have been bhnd at birth 

 owing to no defect in the eyes ; similarly, many have 



525 



