Isaiah Berlin was a British philosopher and political theorist, born on June 6, 1909, in Latvia. He is best known for his work on the concepts of liberty and pluralism. Berlin's influential essay, "Two Concepts of Liberty," distinguishes between negative liberty (freedom from interference) and positive liberty (the ability to act upon one's free will). Throughout his career, Berlin contributed to the fields of history, philosophy, and political thought. He was a prominent figure in the Oxford academic community and served as a professor at Oxford University. His ideas continue to shape discussions on freedom and individual rights today.