How does Barbara Kingsolver use imagery in The Bean Trees?

Imagery:

“There is no point treating a depressed person as though she were just feeling sad, saying, 'There now, hang on, you'll get over it.' Sadness is more or less like a head cold- with patience, it passes. Depression is like cancer.”

“There were two things about Mama. One is she always expected the best out of me. And the other is that then no matter what I did, whatever I came home with, she acted like it was the moon I had just hung up in the sky and plugged in all the stars. Like I was that good.”