Abstract
Historians have been divided about the origins of Leveller theories concerning natural rights, equality, and democracy. This article gives an account of the monistic natural philosophy outlined by Richard Overton in his pre-Leveller work Mans Mortalitie (1643/44) and demonstrates how his heretical conception of creation provided a metaphysical foundation for his political ideas about the liberty of the subject. Comparisons and contrasts are made with the hermetic idealism of Henry and Thomas Vaughan and the spiritual materialism of Gerrard Winstanley. The most illuminating comparison amongst contemporaries, however, is found in Milton's poetic vision of the cosmos in Paradise Lost (1667).