We have spoken of the part of the work which it is necessary for the sitters to perform in order to And now we shall have something to say concerning the part to be played properly by the spirits wishing to communicate. It must not be supposed for a moment that every spirit is possessed of the necessary knowledge enabling it to communicate easily through a medium, or even to develop the medium so that he may become an efficient channel of communication. Spirits are frequently found to be sadly deficient in such knowledge and experience, and the development of the medium as well as the production of satisfactory phenomena, suffer from this lack. The spirits who seek to use a medium may or may not be fitted for such task. Many spirits are utterly unable to properly develop a medium; some fail by reason of their lack of knowledge, and others fail because of their lack of special aptitude for the task. Differences Among Spirits. A writer on this subject well says regarding this particular point: "Some spirits may lack both knowledge and aptitude; others may have the knowledge, but yet fail from want of the power to control. They may be able to affect one mediumistic person and not another. Likewise, they may be able to use a sensitive medium for one phase of mediumship, and yet be unable to succeed in any other direction. A spirit may be in such conditions that he can produce good physical phenomena; he may, however, try to do so through a sensitive who is fitted only for trance or clairvoyant mediumship, but who does not possess the quality or psychic force for sensuous manifestations. A medium who is naturally qualified for physical demonstrations may persist in desiring trance or inspirational mediumship, and be determined to become a speaker or nothing. Disturbing Elements.