How does Sharon Creech use imagery in Walk Two Moons?

Imagery:

“You can't keep the birds of sadness from flying over your head, but you can keep them from nesting in your hair.”

“A person isn't a bird. You can't cage a person.”

“Being a mother is like trying to hold a wolf by the ears,” Gram said. “If you have three or four –or more – chickabiddies, you’re dancing on a hot griddle all the time. You don’t have time to think about anything else. And if you’ve only got one or two, it’s almost harder. You have room left over – empty spaces that you think you’ve got to fill up.”