Over the quarter of a millennium from the later seventeenth century to the Great War, the phrase ‘civil and religious liberty’ was a pervasive feature of English political language. How and why had the phrase come into being? In 1600 it would have been unintelligible. The alliance of religious with civil liberty became possible only when religious liberty acquired a new meaning and became something like a human right. In this lecture, Blair Worden argues that its emergence has two claims on our attention. It betokened a new conception of the relationship between God and society. And it demonstrates the capacity of political events, and of pressures of political power, to shape developments in intellectual history.