The Enlightenment had a profound impact on European monarchies by challenging traditional authority and advocating for reason, individual rights, and democratic ideals. Philosophers like John Locke, Voltaire, and Montesquieu questioned the divine right of kings and promoted concepts such as separation of powers and natural rights. Enlightenment ideas influenced both the American and French Revolutions, leading to the establishment of constitutional governments and an emphasis on civil liberties. As a result, many monarchs had to adapt to emerging liberal movements, leading to reforms and, in some cases, a decline in absolute monarchy, paving the way for modern nation-states.