“All the thoughts of a turtle are ‘turtle.”
—Ralph Waldo Emerson
The turtle, in John Steinbeck's Grapes of Wrath, begins its unknown quest pulling itself from a dusty ditch, then getting sidewinded by a car and spinning around in a glibbering spinning ride. After this he is captured by the villainous Tom Joad and tied in the eternal binds of a heavy winter coat; he escapes and is captured again, this time with little hope of a final escape. But, in the end of his appearance, he is freed, and though briefly chased by a hungered orange cat, he continues on to his goal. At the end, he continues on his reptilian pursuit of the mysterious end.
The turtle’s adventure mirrors the journey of the Joad family through the Midwest. In the beginning the family rips themselves from the dusty land—just as the turtle pulled himself over the embankment. The family is then shocked—one could say sidewinded—by the heartlessness (and the heartless technology) of the world beyond their dust pits, just as the turtle was spun about by his own encounter with modern machinery.
Then, the family lived at two different styles of styles of camp—escaping from the first in the dead of night as the proper Law Enforcement agencies burnt the Red Hostel Camp to the rich Californian earth. The second camp held them tighter in communist grip than before as the darkly eternal philosophy of Karl Marx took its tool on the family and others at the camp. Surely this grip of the camps and its change of their philosophy directly relates to the captured turtle vainly attempting to escape (twice, no less) from the against-nature bonds of young Joad’s coat.
In the closing events of the novel, the Joad family escape from a raging flood that dashes the family; though the flood has, in some ways, the ability to end their lives, it does not because the family finds shelter in a barn. The turtles final events, find him chased by a cat, which he avoids by closing himself up In his scute shell. Consider the connection between cat and flood, both serve as a near life ending experience, yet are arrayed directly against each other for the simple reason that cats hate water.
Thus the turtle serves as a symbolic foreshadowing of the exploits of the Joad family. As to why Steinbeck included such a monstrosity, I can only think that he wished to earn the awards for his novel by adding in such blatant foreshadowing.