THE study of ideas in historical context and the exploration of print culture have been two of the most productive recent preoccupations in the historiography of seventeenthcentury England. The period 1640-1700 was a momentous era for political thought and for the printing press, yet there has been no extended examination of ideas of liberty of the press reaching across these years. The omission allows the persistence of a whiggish view of press freedom as the ineluctable unfolding of a universal principle of political liberty, rather than as a product of historical contingency and polemical exigency in which the role of religious controversy was central. My account argues that an emphasis on ideas as interventions in a historical setting shows how claims for liberty of the press were most frequently and forcefully premised on a distincrion between religious ideas and political actions, rooted in the separation of spiritual and temporal. This offered a response to the opponents of press freedom, who more readily fused religious and political expression, insisting particularly that the conjunction of paper war and civil war in the 1640s proved that no distinction could safely be made - although by arguing this in print they injected ambiguity into their own opposition to the press. The porous frontier between the religious and political, and between conscience and action, provided the casus belli for the debate on free expression, and was inseparable from the wider events and intellectual confrontations of the period. The account surveys arguments for and against liberty of the press, by writers canonical and marginal, from the mid-century paper warfare to the aftermath of the demise of pre-publication licensing at the end of the century. It questions the secularised treatment of the customary canon of Milton and the Levellers, and explores the way print conflict drew Charles I and his supporters into placing a stress on communication as much as press control. In the Restoration period the public memory of paper war vied with the spectre of clerical impositions on conscientious publication, a contest reflected in attitudes towards the imposition of 'popish' press licensing and religious conformity, and in the echoes of the civil war debate in the 'second paper war' after 1678. The competing claims of communication and control, and the polemical struggle to defme the nature of conscience, judgement and reason, imbued the anglican print assault on catholicism during James II's reign, presaging the wider debate on church orthodoxy, rational religion and liberty of the press in the fmal decade of the century.