On Liberty (1859) by John Stuart Mill is a foundational work of liberal political philosophy. The essay argues for protecting individual freedom against the tyranny of the majority and excessive government control. Mill introduces the famous "harm principle," asserting that individuals should be free to act as they wish unless their actions harm others. He passionately defends freedom of thought, speech, and personal lifestyle, contending that even unpopular opinions are essential to discovering truth and driving human progress. The work also explores the limits of societal authority and celebrates individuality. It remains one of the most influential defenses of personal liberty ever written.
