The Constitution of Liberty is Hayek’s monumental restatement of the principles of classical liberalism. Hayek is arguably the most important libertarian thinker of the 20th Century, and The Constitution of Liberty is the most thorough and accessible summary of his thought. Hayek’s major contribution is in understanding the way that knowledge operates within a society and how unplanned and emergent behaviors and institutions are better able to draw upon knowledge held by individuals than are bureaucrats and central-planners. The Constitution of Liberty sets out his vision for what a free society respecting these principles would look like.