According to Wikipedia: "Upton Beall Sinclair Jr. was an American writer who wrote nearly 100 books and other works in several genres. Sinclair's work was well known and popular in the first half of the 20th century, and he won the Pulitzer Prize for Fiction in 1943.
In 1906, Sinclair acquired particular fame for his classic muck-raking novel The Jungle, which exposed labor and sanitary conditions in the U.S. meatpacking industry, causing a public uproar that contributed in part to the passage a few months later of the 1906 Pure Food and Drug Act and the Meat Inspection Act. In 1919, he published The Brass Check, a muck-raking exposé of American journalism that publicized the issue of yellow journalism and the limitations of the "free press" in the United States. Four years after publication of The Brass Check, the first code of ethics for journalists was created. Time magazine called him "a man with every gift except humor and silence". He is also well remembered for the line: "It is difficult to get a man to understand something, when his salary depends upon his not understanding it." He used this line in speeches and the book about his campaign for governor as a way to explain why the editors and publishers of the major newspapers in California would not treat seriously his proposals for old age pensions and other progressive reforms."