There is a long conceptual tradition that interprets phenomena such as clairvoyance and apparitions as evidence for a spiritual component in human beings. Examples of this appear in the literatures of mesmerism, Spiritualism and psychical research. The purpose of this Classic Text is to present excerpts from a book by French astronomer Camille Flammarion touching on this perspective. They are selected from the introduction and conclusion of Flammarion's L'Inconnu: The Unknown (1900), a translation of L'Inconnu et les problèmes psychiques (1900), in which he published and commented on cases of apparitions and other phenomena he collected. In his view, these phenomena showed the existence of the soul. Similar beliefs regarding ideas of the nonphysical nature of human beings and psychic phenomena have continued to the present.
Keywords: Apparitions; Camille Flammarion; L’Inconnu: The Unknown; death coincidences; spiritual phenomena.