Here's a pop quiz for anyone who calls the Rev. Martin Luther King Jr. an American hero.
Can you name any of his great speeches or written works without citing "I Have a Dream" or the "Letter from Birmingham Jail"?
Most Americans would likely flub this quiz. King may be a national hero whose birthday the country commemorates on Monday, but to many he remains a one-dimensional hero -- the vast body of his work unknown. Though he wrote five books and delivered up to 450 speeches a year, he's defined by one speech and one letter.
What then are the great works by King that never get the attention they deserve?
Letter to Coretta
Written on July 18, 1952, to his future wife, Coretta Scott, in which King revealed some surprising thoughts on capitalism and communism.
Why it's important: There's a theory that King adopted more radical economic theories in the last three years of his life. But King's 1952 letter reveals he was radical far earlier than most people realize.
What he said: The letter is an intriguing mix of the personal and abstract. King woos his future wife by telling her: "My life without you is like a year without a springtime which comes to give illumination and heat to the atmosphere which has been saturated by the dark cold breeze of winter."
He then switches gears and starts praising a recent book on economics he has read. He says he would "certainly welcome the day to come when there will be a nationalization of industry ... and a better distribution of wealth."
Signature lines: "I imagine you already know that I am much more socialistic in my economic theory than capitalistic. And yet I am not so opposed to capitalism that I have failed to see its relative merits. It started out with a noble and high motive, to block the trade monopolies of nobles, but like most human systems it falls victim to the very thing it was revolting against. So today capitalism has outlived its usefulness. It has brought about a system that takes necessities from the masses to give luxuries to the classes."
What others say: "King steered toward socialism early on," says Michael G. Long, author of "Christian Peace and Nonviolence: A Documentary History."
"He's speaking about the need for the demise of capitalism, the need to nationalize industries. Early on he has this dream that equality won't happen in America until there's a radical redistribution of wealth."
'Where Do We Go From Here: Chaos or Community'
King's fifth book was published in 1967
Why it's important: This is King's last -- and most radical -- book. By 1967, he was organizing a "Poor People's Campaign," a plan to dispatch an interracial army of poor people to occupy Washington and force the U.S. government to address poverty.
What he said: He takes on black nationalists who ridiculed nonviolence. He says the passage of civil rights laws is not enough. The country must institute a "massive, new national program" to attack poverty. He predicts the civil rights movement will go international as oppressed peoples in other countries adopt nonviolent tactics to combat America's "economic colonialism."
Signature lines: "White Americans must recognize that justice for black people cannot be achieved without radical changes in the structure of our society. The comfortable, entrenched, the privileged cannot continue to tremble at the prospect of change of the status quo. ... This is a multiracial nation where all groups are dependent on each other. ... There is no separate white path to power and fulfillment, short of social disaster, that does not share power with black aspirations for freedom and human dignity."
What others say: "I get so tired of people turning Dr. King into a dreamer," says Doreen Loury, a sociology professor at Arcadia University in Pennsylvania, who says she was blown away by the book when she first read it in the 1960s. "They made him safe. He was a revolutionary."