What is the theory behind reincarnation?

The soul in the reincarnated state is a definite ego—the resident of a physical body on this plane. 

It comes here only on astral visits or in lofty lifting up of spirit when cosmic consciousness inspires the soul. 

Reincarnation is always the ladder of the higher life let down to those who require a step to ascend. 

The reincarnates are always leverages to raise the masses of the people.

—Hartley Coleridge In Spirit

Light is reflected on the particles of earth emanations, as the camera obscura catches the vision one aims the lens at. 

Now we have an article here we call a vision instrument of thought, projecting images of matter. 

This instrument consists of powerful lenses, which peer through the ether of so-called space. It is not retarded by any solid substance because it is one of the so-called x-rays. The violet ray is also involved. 

This instrument is the miniature replica of the soul vision in the clairaudient state, so it is not affected by time, distance, space―or any of the laws, which obtain on your plane. 

But it has to you one radical, extremely interesting feature. It is controlled absolutely by thought. It is on a par with the thinking book publishing machine the authors here use. It gives to those who understand it a vision on all planes, from the fifth to the hundredth, of the actions, environments, thought and love-light of those people who become en rapport or in concert with our plane.

—Hartley Coleridge In Spirit

Wallace, we have been told that on the Twentieth Plane they use instruments to assist them in the process of communicating with us. Can you not tell us so that we can understand the precise principles underlying and governing the process of communication?

This is the modus operandi as I can vibrate it to you. I am here on a plane about five hundred miles above your world. I am speaking now through a process of thought into a delicate instrument, which sends out wave vibrations, exactly in the same way as a Marconi instrument sends waves out to a receiving station instrument.

Is it not possible that some day we might be able to invent an instrument that would receive mechanically your messages and also transmit to you our thought waves?

The use of physical material to act as receiving station can never be. We have a rate of intensity, which must be reduced and only the soul is capable of receiving and interpreting such waves.

—A. R. Wallace In Spirit