Rufus Jones' promotion of mysticism and his novel formulation of the Inner Light, which saw God as an inherent part of human nature, were sweepingly influential within liberal Quakerism in the early 20th century and have had long-lasting effects on Quaker faith and practice. In spite of the importance of his ideas, however, they have received little critical attention. In Mysticism and the Inner Light, Helen Holt provides a systematic analysis of Jones' thought in historical context, showing how he attempted to synthesize his own experience with aspects of the psychology of William James, the idealism of Josiah Royce, and liberal Christianity. She finds that because Jones presented his ideas informally, he is sometimes misinterpreted, especially regarding his views on Christ and humanism. The book draws on Jones' extensive corpus and on unpublished archived letters.