This is a survey of the rule of faith controversy in 17th-century England. The book examines the arguments by which reason eventually became the sovereign standard of truth in religion and politics, and how it triumphed over its rivals: scripture, inspiration and apostolic tradition. The book argues that the main threat to the authority of reason in 17th-century England came not only from dissident groups, but also, and chiefly, from the Protestant theology of the Church of England. The triumph of reason was the result of a new theology, rather than the development of natural philosophy, which upheld the orthodox Protestant dualism between the heavenly and earthly.