If the man sought be a stranger to the seeker, the latter will need something connected with him to act as a clue--a photograph, a letter written by him, an article which has belonged to him, and is impregnated with his personal magnetism; any of these would do in the hands of a practised seer.
Again I say, it must not therefore be supposed that pupils who have been taught how to use this art are at liberty to set up a kind of intelligence office through which communication can be had with missing or dead relatives. A message given from this side to such an one might or might not be handed on, according to circumstances, but even if it were, no reply might be brought, lest the transaction should partake of the nature of a phenomenon--something which could be proved on the physical plane to have been an act of magic.
Another question often raised is as to whether, in the action of psychic vision, there is any limitation as to distance. The reply would seem to be that there should be no limit but that of the respective planes. It must be remembered that the astral and mental planes of our earth are as definitely its own as its atmosphere, though they extend considerably further from it even in our three-dimensional space than does the physical air. Consequently the passage to, or the detailed sight of, other planets would not be possible for any system of clairvoyance connected with these planes. It _is_ quite possible and easy for the man who can raise his consciousness to the buddhic plane to pass to any other globe belonging to our chain of worlds, but that is outside our present subject.
Still a good deal of additional information about other planets can be obtained by the use of such clairvoyant faculties as we have been describing. It is possible to make sight enormously clearer by passing outside of the constant disturbances of the earth's atmosphere, and it is also not difficult to learn how to put on an exceedingly high magnifying power, so that even by ordinary clairvoyance a good deal of very interesting astronomical knowledge may be gained. But as far as this earth and its immediate surroundings are concerned, there is practically no limitation.
Under this rather curious title I am grouping together the cases of all those people who definitely set themselves to see something, but have no idea what the something will be, and no control over the sight after the visions have begun--psychic Micawbers, who put themselves into a receptive condition, and then simply wait for something to turn up. Many trance-mediums would come under this heading; they either in some way hypnotize themselves or are hypnotized by some "spirit-guide," and then they describe the scenes or persons that happen to float before their vision. Sometimes, however, when in this condition they see what is taking place at a distance, and so they come to have a place among our "clairvoyants in space."