Baron de Montesquieu (1689-1755) [pronounced mohn-tes-kee-u'] was a French writer and philosophe on political philosophy who greatly influenced the American Founding Fathers. In The Spirit of the Laws (1748) he proposed the concepts of separation of powers and checks and balances in government; these ideas were incorporated into the United States Constitution. His book, The Spirit of the Laws, explained essential aspects of good government that became enormously influential.
Charles Louis de Secondat, Baron de la Brede et de Montesquieu, was born to a wealthy family of lawyers. He inherited a fortune, a title, and an important judicial office in Bordeaux. As judge for ten years he also developed his interests in philosophy, natural science, and history. In 1721 he published Persian Letters;, a satire on French institutions. Supposedly written by Persian travelers in Europe and their friends, the book was full of witty comments on French society, politics, and religion. Montesquieu quickly became a leading literary figure in Paris. In 1728 he was made a member of the prestigious French Academy. He traveled widely in Europe and spent a year in England.
In 1734 he published Considerations on the Causes of the Greatness of the Romans and Their Decline, emphasizing the strength of republican civic virtue as opposed to the inevitable weakness of tyranny and conquest. This book is one of the first important works dealing with the philosophy of history, and was read by intellectuals across Europe.
Montesquieu greatly admired the British political system, which he considered the finest he had ever seen. The chief passion of the English is their fondness for liberty, which, he says, they "love prodigiously because this liberty is genuine." In defending their freedom, he suggests, the British are no less resolute than were the citizens of classical Rome. For liberty, England is prepared to "sacrifice its goods, its ease, its interests." In a crisis, it will "impose on itself imposts quite harsh, such as the most absolute prince would not dare make his subjects endure." Moreover, possessing as they do "a firm understanding of the necessity of submitting" to these taxes, the English are prepared to "pay them in the well-founded expectation of not having to pay more." The burden they actually shoulder is far heavier than the burden they feel.
Spirit of the Laws
The Spirit of the Laws (1748), his most important work, was greatly influenced by John Locke. Montesquieu undertakes a comparative study of three types of government—republic, monarchy, and despotism. The book is marked by depth, clarity, and brilliant, unadorned style. Abandoning any absolute statement of human nature, it asserted instead that multiple solutions existed to the problems of government and freedom, and that these solutions depended on the differing guiding principles of societies. Its thesis that the powers of government ought to be separated in order to ensure individual freedom had a strong influence on the writers of the Constitution of the United States
He had a strong influence on the ideas of classical liberalism (which resemble libertarianism and modern conservatism in some ways).
- "The deterioration of a government begins almost always by the decay of its principles." - Spirit of the Laws, VIII, Ch. 1
- "Democracy has, therefore, two excesses to avoid - the spirit of inequality, which leads to aristocracy or monarchy, and the spirit of extreme equality, which leads to despotic power, as the latter is completed by conquest." 
- Aron, Raymond. Main Currents in Sociological Thought: Montesquieu, Comte, Marx, Tocqueville, the Sociologists and the Revolution of 1848 (1965) by conservative French scholar online edition
- Courtenay, C.P. Montesquieu and Burke (1963), good introduction
- Kingston, Rebecca E. Montesquieu and His Legacy (2009) excerpt and text search
- Shklar, Judith M. Montesquieu (1987). 136 pp. the best introduction
- Strauss, Leo, and Joseph Cropsey. History of Political Philosophy (1963), by neoconservative scholars online edition
- Baum, John Alan. Montesquieu and Social Theory (1979) 191 pp.
- Carrese, Paul. "Montesquieu's Complex Natural Right and Moderate Liberalism: The Roots of American Moderation," Polity, Vol. 36, 2004 online edition
- Krause, Sharon. "The Politics of Distinction and Disobedience: Honor and the Defense of Liberty in Montesquieu," Polity, Vol. 31, 1999 online edition
- Pangle. Thomas L. Montesquieu's Philosophy of Liberalism: A Commentary on The Spirit of the Laws (1989), by a leading conservative scholar; "Liberalism" in this sense is close to modern conservatism. excerpt and text search
- Rahe, Paul Anthony. Montesquieu and the Logic of Liberty: War, Religion, Commerce, Climate, Terrain, Technology, Uneasiness of Mind, the Spirit of Political Vigilance, and the Foundations of the Modern Republic (2009) by a leading conservative scholar excerpt and text search
- Stark, W. Montesquieu: Pioneer of the Sociology of Knowledge (1960) by conservative sociologist online edition
- Montesquieu. The Spirit of the Laws ed by Anne M. Cohler et al. (1989), excerpt and text search
- Montesquieu. Considerations on the Causes of the Greatness of the Romans and Their Decline (1999) excerpt and text search
- Montesquieu. Selected Political Writings ed. by Melvin Richter (1991) excerpt and text search
- Montesquieu. Persial Letters (2009), excerpt and text search
- Paul A. Rahe, "Empires: Ancient and Modern," The Wilson Quarterly Volume: 28$3 (Summer 2004) pp 68+ online
- HOYT'S NEW CYCLOPEDIA OF PRACTICAL QUOTATIONS
- The Spirit of Laws, with d'Alembert's analysis of the work, tr. by T. Nugent, Volume 1, 1878
- Works by Charles-Louis de Secondat, baron de La Brède et de Montesquieu - text and free audio - LibriVox