A mystical experience, no matter what else, is a subjective occurrence in the psyche. However, when it appears in the psychoanalytic consulting room, its origin, content, and meaning are unknowable. Yet it is there in the room, and it must be addressed. It is not a minor illusion but rather one that requires attention as its occurrence may lead to a profound alteration of consciousness and, as Carl Jung suggests, a cure for neurosis. Leslie Stein interviewed twenty-nine mystics in order to understand the origin, progression, phasing, emotions, and individual variations of a mystical experience in order to make sense of how it should be addressed, the appropriate analytic attitude in the face of a mystery, the way to work with its content, and its psychological meaning. In doing so, he uncovered that there may be specific development markers that create a proclivity to be receptive to such an experience that has clinical significance for psychoanalysis.