The turtle is also a parallel to Jim Casy, a traveler with the family, since they are both described as having tight necks and faces, and humorous eyes.
Grapes are used many times in the novel to symbolize the anger of the migrants and the truth about the journey's destination. Since grapes will burst when they get too ripe, the use of the phrase "grapes of wrath- represents what the migrants will do with their bitterness and frustrations with the California farmers. The grapes also represent the theme that no matter how nice California seems, it only appears that way but is actually rotten inside. Just as grapes can give that impression of freshness, so can the hopes and dreams of the migrants who think they'll get a new start in California. Grampa Joad even talks about sitting in a tub of grapes, enjoying them like a little kid, showing the family's optimism about the trip West. In the beginning of the novel, grapes are a symbol of a fresh start and the family start out with a positive outlook on their journey, but they slowly find that their destination seems more and more rotten everyday. The good, fresh grapes that they dream of soon turn into bad, rotten grapes of wrath and bitterness since their journey turns into more of an obstacle course full of deaths and saddness. There are references to grapes in the bible. Specifically, in Revelation 14:18, which talks about grapes and God's anger. In the bible, old grapes are destroyed to produce new grapes, all symbolizing the struggle of good and evil.
Steinbeck uses many biblical symbols in this novel aside from the grapes. One such symbol is in his main characters. The entire Joad family, all twelve members on the journey, are representative of the twelve tribes of Israel's trip to the "promised land- through the desert. Like the tribes, the Joads must travel through the desert, except the Joads get no reward. Jim Casy is used as a symbol of Jesus Christ.
