"William Penn played a crucial role in the emergence of religious liberty and remains a singular, if often overlooked, figure in the history of liberty of conscience. Penn's political thought provides a window into the tolerationist movement that gained strength over the second half of the seventeenth century. In addition, Penn experienced firsthand the complex relationship between political theory and practice as proprietor of a major American colony. A careful examination of Penn's political thought points scholars toward a new way of understanding the enterprise of political theory itself"--