Listen to what careful thinkers have said concerning the possibility of entire worlds existing in the same space occupied by us, but of which we are unconscious by reason of our failure to sense their vibrations: One says, "All our sensations are due to the impact upon our sense-organs of vibrations in some form. Variations in the strength and rapidity of these vibrations constitute the difference in our perceptions. Our range of response is but a limited one. Some vibrations are too rapid and some too slow to affect our senses, and therefore we have called to our aid various mechanical contrivances which enable us to recognize existences which would otherwise remain unknown. But it is still conceivable that there may be, and doubtless are, conditions of vibratory energy that escape us, and which, if we could develop finer senses, would yield wonderful results and extensions of our power and knowledge. Today, indeed, we are coming into contact with forces, possibilities, and personalities which amount to a revelation of a new universe of things." Interpenetrating Planes and Worlds. Another says: "It is true that 'things are not what they seem'; but everything seems to be 'thus and so' to us only because of its particular plane of being, and that plane of being is determined by its vibrations. On one plane there is a certain vibratory value or speed; on another plane, a different one; but a plane is not a place, but a state, and so it is possible that two utterly different planes of being might co-exist in the same place and be entirely unknown to one another. That may seem absurd, but it is a scientific truth, and many authorities have endorsed the same." Another says: "There may be, right here and now, passing through us and this world, some planet invisible to us, with mountains, oceans, lakes, rivers, cities, and inhabitants: and yet we know absolutely nothing of their existence." Another says: "Some students of the occult find it difficult to grasp the idea of a number of manifestations, each having its own rate of vibration, occupying the same point of space at the same time. A slight consideration of the phenomena of the physical world would perhaps aid such persons in assimilating the concept in question. For instance, as every student of physics knows, a single point of space may contain at the same time vibrations of heat, light of many shades, magnetism electricity, X-Rays, etc., each manifesting its own rate of vibration, land yet none interfering with the others."