How does Joanne Greenberg use imagery in I Never Promised You a Rose Garden?

Imagery:

"For a glimpse of their true value they had only to look into their neighbors' eyes or to hear Pop's remarks if the soup was cold..."

She liked working with patients. Their very illness made them examine sanity as few 'sane' people could. Kept from living, sharing, and simple communication, they often hungered for it with a purity of passion that she saw as beautiful.