This article traces the connection between William James's writings in "The Varieties of Religious Experience" and Jean Piaget's work on moral development through Piaget's early work on religious experience. James characterises religious experience as unlocking deep personal power that can sustain a "strenuous mood". These ideas impacted the early work of Piaget on religious experience through the influence of Henri Bergson and Theodore Flournoy, both friends of James. The shared depth-psychology approach to religious experience of James and Piaget is important to current debates on spiritual and moral education. (Contains 3 notes.)