First published in 1920, The Planet Mars and Its Inhabitants: A Psychic Revelation is a book by J. L. Kennon who, whilst under the power of trance, channelled the words of Eros Urides, a Martian. The medium was held in trance for short periods only, as "the medium must necessarily experience the atmosphere of Mars which is more rarified than that of your Earth" and apparently the medium seemed to have some difficulty, and at first pain in breathing while in the trance condition. In 1920 it was decided to write the book in which the Planet Mars, its people, its form of government, its Art, Industries, Philosophy of life, etc. would for the first time in the history of this world be given.