The third book of the Sutras is the Book of Spiritual Powers.
These spiritual powers can only be gained when the development described in the first and second books has been measurably attained. For only after this is the spiritual man so far grown, so far disentangled from the psychical bandages and veils which have confined and blinded him, that he can use his proper powers and faculties. For this is the secret of all spiritual powers: they are in no sense an abnormal or supernatural overgrowth upon the material man, but are rather the powers and faculties inherent in the spiritual man, entirely natural to him, and coming naturally into activity, as the spiritual man is disentangled and liberated from psychical bondage, through keeping the Commandments and Rules already set forth.
