The main theme of the Enlightenment period in European history was the emphasis on reason, individualism, and skepticism of traditional authority. Intellectuals, known as philosophes, encouraged critical thinking and challenged the established norms of society, including monarchy and the Church. Enlightenment thinkers like John Locke, Voltaire, and Rousseau promoted ideas of liberty, equality, and democratic governance. This intellectual movement played a crucial role in shaping modern political thought and laid the groundwork for revolutions in America and France, pushing towards the ideals of human rights and scientific rationalism that continue to influence contemporary societies.