The Enlightenment was a period in the 18th century where philosophers used reason to understand human problems and nature. They believed reason could solve problems and improve lives. Enlightenment ideals fueled the American and French Revolutions by promoting ideas like natural rights, consent of the governed, and limited government. Major Enlightenment philosophers included Thomas Hobbes, John Locke, Jean-Jacques Rousseau, Montesquieu, Voltaire, and later Adam Smith and Mary Wollstonecraft. Some monarchs also adopted Enlightenment ideals by becoming more tolerant and just rulers.