About the author (from wikipedia):
Charles-Louis de Secondat, Baron de La Brède et de Montesquieu (1689 – 1755), was a French lawyer, man of letters, and political philosopher who lived during the Age of Enlightenment. He is famous for his articulation of the theory of separation of powers, which is implemented in many constitutions throughout the world. He did more than any other author to secure the place of the word despotism in the political lexicon.
De l’Esprit des Lois (The Spirit of the Laws) was originally published anonymously in 1748. The book quickly rose to influence political thought profoundly in Europe and America. In France, the book met with an unfriendly reception from both supporters and opponents of the regime. The Catholic Church banned l’Esprit – along with many of Montesquieu’s other works – in 1751 and included it on the Index of Prohibited Books. It received the highest praise from the rest of Europe, especially Britain.
Montesquieu was also highly regarded in the British colonies in North America as a champion of liberty (though not of American independence). Political scientist Donald Lutz found that Montesquieu was the most frequently quoted authority on government and politics in colonial pre-revolutionary British America, cited more by the American founders than any source except for the Bible. Following the American revolution, Montesquieu’s work remained a powerful influence on many of the American founders, most notably James Madison of Virginia, the “Father of the Constitution”. Montesquieu’s philosophy that “government should be set up so that no man need be afraid of another” reminded Madison and others that a free and stable foundation for their new national government required a clearly defined and balanced separation of powers.
About the Book (from wikipedia):
The Spirit of the Laws (French: De l’esprit des lois) is a treatise on political theory first published anonymously by Charles de Secondat, Baron de Montesquieu in 1748 with the help of Claudine Guérin de Tencin. Originally published anonymously partly because Montesquieu’s works were subject to censorship, its influence outside France was aided by its rapid translation into other languages. In 1750 Thomas Nugent published the first English translation. In 1751 the Catholic Church added De l’esprit des lois to its Index Librorum Prohibitorum (“List of Prohibited Books”). Yet Montesquieu’s political treatise had an enormous influence on the work of many others, most notably: Catherine the Great, who produced Nakaz (Instruction); the Founding Fathers of the United States Constitution; and Alexis de Tocqueville, who applied Montesquieu’s methods to a study of American society, in Democracy in America. Macaulay offers us a hint of Montesquieu’s importance when he writes in his 1827 essay entitled “Machiavelli” that “Montesquieu enjoys, perhaps, a wider celebrity than any political writer of modern Europe.”
Montesquieu spent around twenty one years researching and writing De l’esprit des lois (The Spirit of the Laws), covering many things like the law, social life, and the study of anthropology and providing more than 3,000 commendations. In this political treatise Montesquieu pleaded in favor of a constitutional system of government and the separation of powers, the ending of slavery, the preservation of civil liberties and the law, and the idea that political institutions ought to reflect the social and geographical aspects of each community.