The student who has carefully read what we have said in the earlier portions of the present book regarding the subject of Nature's Finer Forces, and those concerned with "vibrations," and "planes of being," will be able to harmonize the apparently somewhat conflicting opinions of those authorities above quoted concerning the nature of mediumship and spirit communication. In the first place, the student will remember that there exist planes of being higher and other than our own earth-plane, and that the rate of normal vibration on such planes is much higher than are those upon our own earth-plane. In the second place, he will remember that beings dwelling and manifesting on these higher planes are able to communicate only by means of their higher vibratory rate of manifestation. And, in the third place, he will remember that a person dwelling on the earth-plane will not ordinarily register and interpret these higher vibrations of communication; and that it is necessary for such a person to have originally, or else have developed, the capacity to raise his or her own vibrations to the key necessary to "catch" these higher vibrations. In short, we have here once more another instance of that "attunement" between sender and receiver the most common instance of which is the wireless telegraph. Psychic Attunement. The entity, or spirit, dwelling on one of the many higher planes of being who wishes to communicate with persons on earth through a medium, must first select some person capable of raising his or her own vibratory rate of consciousness to become "in tune" with that of the spirit himself. Then he must learn to project his own mental vibrations with sufficient intensity and force to be "caught" by the sensitive perceptive organism of the medium. These things are beyond the understanding and accomplishment of many decarnate spirits, and unless they are taught by some one on their own plane of existence they are likely to fail in their attempts to communicate through a medium on the earth-plane. But at the present time, in view of the great interest being manifested "over there" in the communication with the earth-plane, an earnest, persevering spirit will usually have comparatively little difficulty in finding a proper instructor, and in acquiring the art of "earth-plane communication," as it is called on the spirit plane. The Development of Mediumship.