The legacy of Montesquieu, one of the key philosophers of the Enlightenment, is remarkably diverse. In 1721 he published Persian Letters; in 1734 Considerations on the Causes of the Greatness of the Romans and their Decline, a formidable work of history; and in 1748 The Spirit of the Laws, which represents the essence of many years of research and the fruits of his political and historical reflections. From these works, Montesquieu appears at times as a man of politics, at times as a historian, and at times as a law-maker and jurist. Such range, however, does not detract from the unity of his thought and the connectedness of his reflections, since in all his works he strove to understand the laws governing societies and organizing the course of the phenomena of history and nature, and to observe their effect on human life. In his first work, Persian Letters, Montesquieu dealt with the relationship of religion and law. He established the relativism of beliefs and a topography of precepts and laws, called for religious tolerance, and produced a pluralist discourse for understanding religious and cultural difference. In the second work, Considerations on the Causes of the Greatness of the Romans and their Decline, he dealt with law in its relation to the movement of history, revealing the laws that govern the progress and retrogression of states and civilizations. In his greatest and most renowned work, The Spirit of the Laws, he dealt with law in its relation with various factors that define general laws such as climate, territory, population, economy, morality, religion, and power. These factors combine the material with the ideal, the conceptual with the tangible. They also reveal the dialectical nature of Montesquieu’s thought. He tried to found a comprehensive positivist approach to human and religious history and formulate ideas on the future of institutions and their transformation in real history.