An Apology for the True Christian Divinity

Robert Barclay was an early Quaker theologian, and this 1676 work, first written in Latin and then English, is his own systematic defense of Quaker belief, covering the doctrine of the Inner Light and Quaker objections to outward sacraments and a paid clergy. As Barclay's own primary statement it is the standard text cited for what early Quakerism actually taught in systematic form, at a time when most Quaker writing was occasional and polemical rather than organized theology. Its limit is that it represents one articulate voice's systematic case for the movement at one moment in its formation, not a survey of the diversity within early Quakerism or an account of how Quaker theology developed afterward, so a claim about later Quaker practice needs a more recent source.