Charles-Louis de Secondat, baron de La Brède et de Montesquieu (; ; 18 January 168910 February 1755), generally referred to as simply Montesquieu, was a French social commentator and political thinker who lived during the Enlightenment. He is famous for his articulation of the theory of separation of powers, which is taken for granted in modern discussions of government and implemented in many constitutions throughout the world. He was largely responsible for the popularization of the terms feudalism and Byzantine Empire.