Quakers are chary of doctrine, feeling that it seeks to limit our understanding of God and to shut people out rather than bring them in. In his 1982 Swarthmore Lecture book, the late Gerald Priestland drew upon his experience in exploring the doctrines of the churches for his broadcast series Priestland's Progress. In his talks with more than a hundred thoughtful churchpeople he found doctrine to be far more flexible and useful than many of us suppose. In his own words 'It is not a set of unreasonable certainties, but of reasonable uncertainties. It is a way of packaging and passing on information. It is a set of tools to work with, not a row of idols to worship'. Quakers do not need to hammer out doctrines of their own, but they can be an authentic part of the One Great Church only if they are prepared to come to terms with doctrinal thinking and see what it means.