England has one of the richest and most distinctive histories of medieval mystical experience in all Europe. Resonant echoes of that history linger at places like Walsingham and Norwich. The shrine of the Holy House, destroyed at the Reformation, became one of the leading pilgrimage centres of the Christian west. It emerged out of the visions of Richeldis de Faverches, an eleventh-century Saxon noblewoman, who believed she had been instructed by the...