French writer Simone de Beauvoir laid the foundation for the modern feminist movement. Also an existentialist philosopher, she had a long-term relationship with Jean-Paul Sartre.

Mary Wollstonecraft was an English writer who advocated for women's equality. Her book A Vindication of the Rights of Woman pressed for educational reforms.

Carter G. Woodson was an African-American writer and historian known as the "Father of Black History Month." He penned the influential book The Mis-Education of the Negro.

Author Voltaire wrote the satirical novella Candide and, despite controversy during his lifetime, is widely considered one of France's greatest Enlightenment writers.

Sigmund Freud was an Austrian neurologist best known for developing the theories and techniques of psychoanalysis.

Benjamin Franklin is best known as one of the Founding Fathers who drafted the Declaration of Independence and the Constitution of the United States.

Confucius was an influential Chinese philosopher, teacher and political figure known for his popular aphorisms and for his models of social interaction.

Physician Nostradamus believed that he could predict the future and published his predictions in The Prophecies. Some believe they have or will come true.

Socrates was a Greek philosopher and the main source of Western thought. Little is known of his life except what was recorded by his students, including Plato.

Italian scientist and scholar Galileo made pioneering observations that laid the foundation for modern physics and astronomy.

Communist Leon Trotsky helped ignite the Russian Revolution of 1917, and built the Red Army afterward. He was exiled and later assassinated by Soviet agents.

Horace Mann was an American politician and education reformer, best known for promoting universal public education and teacher training in "normal schools."

Although Hippocrates probably didn't write the famous oath that bears his name, it serves as foundation for the oath medical school graduates take at the start of their careers.

Thomas Paine was an English American writer and pamphleteer whose "Common Sense" and other writings influenced the American Revolution, and helped pave the way for the Declaration of Independence.

Russian author Leo Tolstoy wrote the acclaimed novels 'War and Peace,' 'Anna Karenina' and 'The Death of Ivan Ilyich,' and ranks among the world's top writers.

Louis Braille invented a system of raised dots that enables blind people to read and write. His system is the globally accepted code for those with visual impairments.

Carl Jung established analytical psychology. He advanced the idea of introvert and extrovert personalities, archetypes and the power of the unconscious.

Famed scholar Noam Chomsky is known for both his groundbreaking contributions to linguistics and his penetrating critiques of political systems.

Roger Williams was a political and religious leader best remembered for his strong stance on the separation of church and state and founding the colony of Rhode Island.

James Naismith invented the game of basketball in 1891.

Immanuel Kant was a German philosopher during the Enlightenment era of the late 18th century. His best known work is the 'Critique of Pure Reason.'

Ancient Greek philosopher Plato founded the Academy and is the author of philosophical works of unparalleled influence in Western thought.

Erasmus was the dominant figure of the early humanist movement. Neither a radical nor an apologist, he remains one of early Renaissance controversial figures.

Naturalist, writer and advocate of U.S. forest conservation, John Muir founded the Sierra Club and helped establish Sequoia and Yosemite National Parks.