In a series of five dialogues, Lumen—a disembodied soul—explains to a human questioner the physical and metaphysical basis of life after death as well as describing the experiences made possible in such an afterlife. The first dialogue includes a crude theory of the relativity of time and space, dramatized by observations of Earth made by a soul traveling close to the speed of light. The second includes a history of Earth, unfolding in reverse, as seen from the viewpoint of a soul traveling faster than light.
Lumen explains that the form of the human body results from its adaptation to a specific set of physical circumstances rather than from divine design, and that sentient beings elsewhere in the universe are very different by virtue of being adapted to a wide variety of environments. Lumen also reveals that physical forms are the products of slow and never ending processes of evolution and that the soul is subject to its own evolutionary process. The third and fourth dialogues expand this theme considerably. In them, Lumen explains that the accepted image of the universe is conditioned by the abilities of humans’ senses and that beings equipped with different sense organs would perceive it otherwise.
Lumen offers numerous specific examples to support these arguments, explaining that life on Mercury and Uranus bears no resemblance to life on Earth because one is so close to its sun and the other so far away, whereas worlds orbiting other stars at a distance close to that of Earth from its sun produce similar humanoid inhabitants. There are, however, many variations of the humanoid form. One species described has no need of sexual reproduction, and in another respiration and nutrition are carried out simultaneously by means of the same organs. On another world there are no animals, but intelligent species of plants have evolved.
The fifth and briefest dialogue (added to the later editions as a series of afterthoughts) takes this train of thought further, describing life at the atomic level. It also discusses the soul’s ability to “magnify” time by traveling at nearly the speed of light, such that the universe can be perceived in slow motion. This idea was novel in the days before the invention of the motion picture camera.