We can learn that, in some situations, the working class has to organize to overcome the power of the moneyed class that controls business. In The Grapes of Wrath the workers do not make any progress until they force the landowners and business owners to pay them higher wages by going on strike.
It seems to me one of the lessons of this novel is the ability to give even when you have virtually nothing. Time after time, people who are barely eking out a living are the ones who have the most compassion and do the most giving. It is a good reminder that giving is not dependent on possessions and circumstances.
I completely agree with all the ideas expressed above. There is clearly so much we can learn from this wonderful novel. However, one of the key lessons that this book teaches us is that there is a profound link between man and land. We are shown the turmoil and disaster that occurs when the Joad family are uprooted from their land - their home - and are left without land and are forced to migrate in search of work. Steinbeck is obvioiusly harshly critical of the market forces in play that have brought this about, and argues, as in his other works, that having land gives us security, identity and self-esteem.
The previous posts were well conceived in their ideas. I think that one of the strongest points to come out of the novel is the power of collectivity. When examining the strong hold that material reality has on individuals, one ends up recognizing how individuals succumb to it at the cost of other human beings. This was certainly so in the Great Depression where individual survival took on an adversarial quality. While we marvel at how indviduals perservered and survived through such a painful moment in time, I think that there should be some level of more lauding given to those who looked out for others in such a difficult and trying moment. This is where Steinbeck's work offers powerful insight. The examples of Jim Casy and Tom Joad being figures who offer themselves for and to others is transcendent. In a time where individuals looked out for themselves, Steinbeck's narrative indicates to us that the ability to care for and look out for others is not contingent on economic condition or material reality. When Rose of Sharon feeds a starving man from her own breast milk, it speaks to this element, a lesson to which all individuals can only hope to aspire.
As a socialist himself, John Steinbeck extensively develops the theme of social commitment, that by working together people can help each other. At the beginning of the novel, for instance, Tom wants no involvement with anyone else. But, after his experiences on the way to California and because of his friendship with Casy, Tom assumes a commitment to social justice. Like the turtle who drags himself through the dust, he plants a seed for the future. In Chapter 28 he tells his mother,
"Well, maybe like Casy says, a fella ain't got a soul of his own, but on'y a piece of a big one--an' then--....Then it don' matter. Then I'll be all aroun' in the dark. I'll be ever'where--wherever you look. Wherever they's a fight so hungry people can eat, I'll be there....
The concept of the Oversoul, of which all men are a part, is prevalent throughout Steinbeck's narrative. At the end, Tom understands this. The concept of we as opposed to us or they, has strength and can fight injustice. In unity there is always strength is a lesson.
I agree completely with the answer above; there are countless lessons that can be drawn from The Grapes of Wrath.
Perhaps one of the strongest lessons are the power and necessity of family and community. Of course, we see this ideas expressed primarily through the Joads but also in the interactions of the Joads with everyone else they meet. Some of the most moving moments in the novel are some of the little, seemingly everyday things that individuals do for one another. However, against the backdrop of the poverty of the Great Depression, those things are magnified. For example, the diner cook telling the waitress to sell the man a 15 cent loaf of bread for only a dime. Such a little, seemingly insignificant thing meant that family might have another meal. Or Ma Joad feeding soup to the countless starving children in the camp even though her own family is on the brink of starvation as well. The message throughout the novel seems clear in this regard: no matter how bad things may get, they will most certainly only continue to get worse unless families and communities stick together and look out for one another.
Certainly we can take lessons from The Grapes of Wrath just as we can take lessons from almost all literature. They may not be the lessons specifically intended by the author, but that is also part of the beauty of reading it: we take away from it what we feel is important as individuals.
From my perspective, one of the lessons of this novel is that in today's world, even with this stubborn recession, we don't know how good we have it. The Great Depression redefined poverty. Americans actually starved to death. Today's situation is difficult, to be sure, but it is still nowhere near the level of misery and dislocation as the setting and time period of Steinbeck's tale.
I would also take away the lessons of compassion - that of giving to your fellow man when they are in need, even if you have little to give. There are numerous examples in the book of this taking place.
As a third lesson, I think the novel highlighted how poorly we treat our fellow Americans at times, discriminating against the poor, but also against people from certain regions, from the South, or in this case, against the "Okies" like the Joad family and their rude welcome into California.