Among the most important political philosophers of the Enlightenment (or any time period, for that matter), the breadth of Locke's contributions is staggering. Some of his original ideas on social-contract theory can be found virtually unedited in the US Declaration of Independence. His contributions to the theory of mind and property theory are still discussed and debated today. And his contributions to economics, while less appreciated, were in several respects ahead of their time. Roger Woolhouse's 2007 biography of Locke is recommended.