As the embankment grew steeper and steeper, the more frantic were the efforts of the land turtle. Pushing hind legs strained and slipped, boosting the shell along, and the horny head protruded as far as the neck could stretch. Little by little, the shell slid up the embankment until at last a parapet cut straight across its line of march, the shoulder of the road, a concrete wall four inches high. As though they worked independently the hind legs pushed the shell against the wall. The head upraised and peered over the wall to the broad smooth plain of cement. Now the hands, braced on top of the wall, strained and lifted, and the shell came slowly up and rested its front end on the wall.
– John Steinbeck
The Grapes of Wrath, Chapter 3. A land turtle slowly climbs up a steep embankment to get to the highway. The turtle represents isolation and struggle. It is a metaphor for and symbolizes the Joad family and other migrant families searching for a way out of their poverty and homelessness. The turtle’s journey demonstrates persistence in the face of adversity, hope in the face of hopelessness.