And now the great owners and the companies invented a new method. A great owner bought a cannery. And when the peaches and the pears were ripe he cut the price of fruit below the cost of raising it. And as cannery owner he paid himself a low price for the fruit and kept the price of canned goods up and took his profit. And the little farmers who owned no canneries lost their farms, and they were taken by the great owners, the banks, and the companies who also owned the canneries. As time went on, there were fewer farms. The little farmers moved into town for a while and exhausted their credit, exhausted their friends, their relatives. And then they too went on the highways. And the roads were crowded with men ravenous for work, murderous for work.
And the companies, the banks worked at their own doom and they did not know it. The fields were fruitful, and starving men moved on the roads. The granaries were full and the children of the poor grew up rachitic, and the pustules of pellagra swelled on their sides. The great companies did not know that the line between hunger and anger is a thin line. And money that might have gone to wages went for gas, for guns, for agents and spies, for blacklists, for drilling. On the highways the people moved like ants and searched for work, for food. And the anger began to ferment.

– John Steinbeck

The Grapes of Wrath, Chapter 21. Steinbeck continues his blistering attack on large-scale commercial agriculture, which not only drives Oklahoma sharecroppers into poverty, but small California farmers too. Big companies buy the canneries, underbid the small farmer for his produce and put him out of business. So the small California farmer joins the Dust Bowl migrants in the desperate search to find work and survive. But there is a warning for greedy business owners and banks, who invest profits in putting down rebellion by workers instead of paying them decent wages. By ignoring the growing "murderous" anger of hungry workers, the companies and banks are ensuring their own doom. There is foreshadowing here of a fightback against their inhuman methods.