The Age of Enlightenment (also known as the Age of Reason or simply the Enlightenment) was an intellectual and philosophical movement that dominated the world of ideas in Europe during the 18th century, the "Century of Philosophy".
Some consider Descartes' 1637 statement "I think, therefore I am" to have sparked the period. Others cite the publication of Isaac Newton's Principia Mathematica (1687). French historians traditionally date the Enlightenment to between 1715 and 1789: from the beginning of the reign of Louis XV until the French Revolution. Most end it with the turn of the 19th century. Philosophers and scientists of the period widely circulated their ideas through meetings at scientific academies, Masonic lodges, literary salons, coffeehouses and in printed books, journals, and pamphlets. The ideas of the Enlightenment undermined the authority of the monarchy and the Church and paved the way for the political revolutions of the 18th and 19th centuries. A variety of 19th-century movements, including liberalism and neo-classicism, trace their intellectual heritage to the Enlightenment.
The Enlightenment included a range of ideas centered on reason as the primary source of knowledge and advanced ideals such as liberty, progress, toleration, fraternity, constitutional government and separation of church and state. In France, the central doctrines of the Enlightenment philosophers were individual liberty and religious tolerance, in opposition to an absolute monarchy and the fixed dogmas of the Roman Catholic Church. The Enlightenment was marked by an emphasis on the scientific method and reductionism, along with increased questioning of religious orthodoxy—an attitude captured by the phrase Sapere aude (Dare to know).