This class of phenomena is known better in the Western world by reason of its manifestation in spiritualistic circles in the movement of tables, etc.; the knocking or tapping on tables and doors, etc.; all of which are usually attributed to the work of "spirits," but which occultists know are generally produced, consciously or unconsciously, by means of the power in the medium or others present, sometimes both. I would say here that I am not trying to discredit genuine spiritualistic phenomena--I am not considering the same in these lessons. All that I wish to say is that many of the phenomena commonly attributed to "spirits" are really but results of the psychic forces inherent in the living human being. Under certain conditions there may appear in the case of a person strongly psychic, and also strongly charged with prana, the ability to extend a portion of the astral body to a considerable distance, and to there produce an effect upon some physical object. Those with strong clairvoyant vision may actually perceive this astral extension, under favorable circumstances. They perceive the astral arm of the person stretching out, diminishing in size as it extends (just as a piece of flexible rubber shrinks in diameter as it expands in length) and finally coming in contact with the physical object it wishes to move or strike. Then is seen a strong flow of prana along its length, which (by a peculiar form of concentration) is able to produce the physical effect. I cannot enter into the subject of astral physics at this place, for the subject is far too technical to be treated in lessons designed for general study. I may at least partially explain the phenomenon, however, by saying that the projected astral arm acts in a manner almost precisely like that of an extended physical arm, were such a thing possible in nature. This astral-body extension produces spirit raps on tables; table-tilting and movement; levitation, or the lifting of solid objects in the air; playing upon musical instruments such as the guitar, accordian, etc. In some cases it is able to actually lift the person himself from the floor, and carry him through the air, in the same way. It may also cause the movement of a pencil in a closed slate, or bit of chalk upon a blackboard. In fact, it may produce almost any form of movement possible to the physical hand. In the case of the levitation of the person himself, the astral arms, and sometimes the legs as well, extend to the floor and push up the physical body into the air, and then propel it along. There are many complex technical details to these manifestations, however, and in a general statement these must be omitted.