Psychologists suggest that to cure cruelty

According to the writer there is a close relationship between

1. 
   the development of the eye and how much rest a person gets
   
2. 
   the health of a person's eyes and his success
   
3. 
   a person's age and how easy it is to detect eye trouble
   
4. 
   the shape of the eye and its ability to cope with modern life
   

2. The writer states that people in modern societies

1. 
   rarely do any outdoor activities
   
2. 
   have much healthier eyes than in the past
   
3. 
   believe that having perfect vision is a sign of success
   

D) live approximately twice as long as did those in "primitive ones