The passes should be conducted on magnetising principles; that is, from the extremities to the gastric region to bring on somnolency, and from the same region to the head and feet or extremes to awaken; from head to foot is unscientific, and might be prejudicial; the central region of the body should be considered _the mesmeric insuperable line_. Cross passes having been found efficient are not anomalous, by reason of the nerves and branches lying in all directions. VISION. According to the popular opinion, which governs the philosopher, and with which the established philosophy agrees, vision is an act performed by the eye, which is said to be endowed with the faculty of sight, by which it is enabled to look into, through space, and see external bodies made visible when covered with solar or day light; nothing of which is true. The eyeball is not possessed of sight; to see is not the function of the sense; externals are not visible; there is no material light; light is a sensible or mental effect consequent on the chromatic organ of the brain being excited by the fluid of the optic nerve. All we know by means of the optic sense, consists in the sensation of light or coloured light, accompanied with the idea of form. The object which promotes the sensation being, seemingly, the place of the sensation, all imagine the sensation is the colour of the object to which the eye is directed, and hence, that the object or body is seen by the eyes. These general mistakes are made evident and stand corrected by reference to the sense itself, its physiology and function, as previously stated and advised. The medium of space is the visual medium; not, however, for looking through, as is supposed, but by reason of it forming the link or intermediate means by which the object is connected with the sense. Now, as the medium of space is present everywhere, and as it promotes visual or optic perception, the question naturally arises, why do we not see in the night as well as day, in all places and at all times; in a word, why do we not see in the dark? The clairvoyant does "see" in the dark.