1899. The lessons in the volume form a rationale or system of instruction for the unfoldment of the spiritual power (the natural endowment of all souls), commonly designated Clairvoyance. Lessons include: Clairvoyance, Its Definition and Office; Clairvoyance, Its Nature and Law of Manifestation and Expression. The Trance; Clairvoyance and Intuition Compared and Correlated; The Spirit Limited in Matter; The Science of Optics, Materially and Spiritually Considered; and Vibrations, Their Law in Relation to Light and Sight.