This is the beginning—from "I" to "we". If you who own the things people must have could understand this, you might preserve yourself. If you could separate causes from results, if you could know that Paine, Marx, Jefferson, Lenin were results, not causes, you might survive. But that you cannot know. For the quality of owning freezes you forever into "I", and cuts you off forever from the "we".
— Chapter 14
Steinbeck was known to have borrowed from field notes taken during 1938 by Farm Security Administration worker and author Sanora Babb. While Babb collected personal stories about the lives of the displaced migrants for a novel she was developing, her supervisor, Tom Collins, shared her reports with Steinbeck, then working at the San Francisco News. Babb's own as-yet unpublished novel, Whose Names Are Unknown, was eclipsed in 1939 by the success of The Grapes of Wrath, and was shelved until it was finally published in 2004, a year before Babb's death.
The Grapes of Wrath developed from The Harvest Gypsies, a series of seven articles that ran in the San Francisco News, from October 5 to 12, 1936. The newspaper commissioned that work on migrant workers from the Midwest in California's agriculture industry. (It was later compiled and published separately.)
While writing the novel at his home, 16250 Greenwood Lane, in what is now Monte Sereno, California, Steinbeck had unusual difficulty devising a title. The Grapes of Wrath, suggested by his wife Carol Steinbeck, was deemed more suitable than anything by the author. The title is a reference to lyrics from "The Battle Hymn of the Republic", by Julia Ward Howe:
Mine eyes have seen the glory of the coming of the Lord: He is trampling out the vintage where the grapes of wrath are stored; He hath loosed the fateful lightning of His terrible swift sword: His truth is marching on.
These lyrics refer, in turn, to the biblical passage Revelation 14:19–20, an apocalyptic appeal to divine justice and deliverance from oppression in the final judgment. This and other biblical passages had inspired a long tradition of imagery of Christ in the winepress in various media.
And the angel thrust in his sickle into the earth, and gathered the vine of the earth, and cast it into the great winepress of the wrath of God. And the winepress was trodden without the city, and blood came out of the winepress, even unto the horse bridles, by the space of a thousand and six hundred furlongs.
The phrase also appears at the end of chapter 25 in The Grapes of Wrath which describes the purposeful destruction of food to keep the price high:
and in the eyes of the hungry there is a growing wrath. In the souls of the people the grapes of wrath are filling and growing heavy, growing heavy for the vintage.
The image invoked by the title serves as a crucial symbol in the development of both the plot and the novel's greater thematic concerns: from the terrible winepress of Dust Bowl oppression will come terrible wrath but also the deliverance of workers through their cooperation. This is suggested but not realized within the novel.