Modern republicanism - distinguished from its classical counterpart by its commercial character and jealous distrust of those in power, by its use of representative institutions, and by its employment of a separation of powers and a system of checks and balances - owes an immense debt to the republican experiment conducted in England between 1649, when Charles I was executed, and 1660, when Charles II was crowned. Though abortive, this experiment left a legacy in the political science articulated both by its champions, John Milton, Marchamont Nedham, and James Harrington, and by its sometime opponent and ultimate supporter, Thomas Hobbes. This volume examines these four thinkers, situates them with regard to the novel species of republicanism first championed in the early 1500s by Niccolò Machiavelli, and examines the debt that he and they owed the Epicurean tradition in philosophy and the political science crafted by the Arab philosophers Alfarabi, Avicenna, and Averroës.