There is another power open to the Psychomancer along the lines of Simple Psychomancy. We refer to the phenomena of "seeing into" the physical bodies of other people; examining the internal organs; diagnosing diseases, etc. Of course, in this case, before the Clairvoyant is able to correctly diagnose a disease he must be acquainted with the nature of the organs, and their appearance in their normal state, etc., so that he will recognize a diseased condition when he sees it. One must needs have an acquaintance with Anatomy and Physiology, as well as possessing trained Psychomantic powers for this work. LESSON IV. THE ASTRAL TUBE. The term, "~The Astral Tube~," is frequently met with in the writings of Occultists, but you will find very little more than a mention of it in many of such works, the proverbial caution of the older writers having acted in the direction of preventing their entering into a fuller description or explanation, for fear of the information falling into improper hands. This will be more readily understood, when we tell you that the Astral Tube is, and may be, used for classes of phenomena other than that of Psychomancy, notably that of Mental Influencing, "treating", etc., which however forms no part of the present work, but which will be discussed in a future volume of the series to be called "Mental Influence, etc." The Astral Plane is composed of an ethereal form of matter, very much rarer and finer than the matter of the Physical Plane--but matter, nevertheless, and subject to fixed laws and conditions. And, just as it is possible to establish "lines of force" in the physical matter, so may corresponding "lines of force" be established in Astral matter. And this Astral Tube is really such a "line of force." In other words, it is possible to set up and establish a "line of force" on the Astral Plane, that will serve as a ready conductor of Astral vibrations, currents, etc., and which affords a highly efficient channel of communication between objects far removed from each other in space. And this channel is actually created and used in a variety of forms of Occult phenomena. POLARIZATION. You have heard of "Polarity," and "Polarization" in connection with electrical phenomena. "Polarity" is defined by Webster as: "That quality or condition of a body by virtue of which it exhibits opposite or contrasted properties or powers, in opposite or contrasted parts or directions; or, a condition giving rise to a contrast of properties corresponding to a contrast of positions." And, "Polarization" is defined by the same authority as: "Act of polarizing; state of having polarity." Well, then, the process of erecting the Astral Tube is practically that of the "polarization" of the particles of Astral matter by an effort of the human Will, set in motion by means of a strong Desire or Determination, under certain conditions.