Charles-Louis e Secondat, baron de La Brède et de Montesquieu (January 18, 1689 in Bordeaux – February 10, 1755), was a French social commentator and political thinker who lived during the Era of the Enlightenment. He is famous for his articulation of the theory of separation of powers, 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.