A key figure in the development of the philosophy of liberalism is John Locke. His writings in the 17th century emphasized notions of individual rights, government by consent, and the protection of private property. Locke's ideas laid the foundation for modern democratic thought, influencing both the American and French Revolutions. His belief in the importance of reason, equality, and freedom remains central to liberal philosophy, advocating for a social contract that secures individual liberties and limits governmental power.