Now then, understanding this law, we will be very careful in all our investigations of communication to distinguish between the presence of the thing itself and the presence of that which represents it. Did I wish to communicate with a Spirit, who has unfolded in him a Spirit-consciousness, which can be addressed in another way than through the physical eye or ear or touch, and being so divested of this physical form that my mind comes in absolute contact with this Spirit-medium which permeates all space, and which internally and spiritually corresponds to light external and physical, and passes freely through bodies opaque to light—then my Spirit-form acts upon that Spirit-medium which is not impeded by this wall, but which passes through it as light through transparent glass, carrying my image with it. We say that glass is transparent, because light passes freely through it, and brings the image of that which it would represent. We see an individual or tree coming freely through the glass into the room. Now if we have a medium which will pass as freely through a board, then that board is as transparent to that medium as glass is to light. The magnetic medium, by which the magnetic needle is influenced, passes freely through a board even; therefore to that medium the board is as transparent as glass is to light. It is also well to understand that this nerve-medium, as well as the spiritual medium corresponding to the mind—which is to the mind what the medium of light is to the eye—passes freely through these opaque bodies. Therefore the individual brought in contact with this medium will see Spirit-existences, not by their presence in the consciousness, but by that which represents the presence there. Hence it is that the clairvoyant (when you have proceeded with your manipulation until you have insulated the mind, or brought it into clear _rapport_ with this spiritual medium or atmosphere so that he sees by the spiritual sight and hears with the spiritual ear, and no longer sees with the physical eye, or hears with the physical ear) comes in contact with this spiritual medium, and can look out into another room, and tell what is transpiring, who is there, etc., just as we can look through glass and tell what we see. The principle is precisely the same. The medium by which he perceives things in another room freely permeates or passes through the intervening walls; so that although my spiritual form is still in this body, yet it is actually exerting its influence on this spiritual medium throughout the world—throughout not only this world, but throughout the solar system. Wherever this spiritual medium extends, this spiritual image of mine is taken and carried out through that medium, just as my physical image is carried out through the medium of light; and whoever comes into _rapport_ with that Spirit-medium and influence, and undulates to the same motion, will perceive that form. Hence coming into the clairvoyant condition