In chapter XV of the Book of Mediums, author Allan Kardec explains that of all forms of communication between the incarnates (spirits in the physical body) and the spiritual plane (the various spiritual worlds where the spirits reside), the handwriting of the spirits by the hand of the medium is the simplest, the most comfortable, and especially the most complete.
Most of the coding organized by Allan Kardec was based on psychography, revelations written by mediums in various parts of the world clarified the researcher's doubts about the relations between the material and spiritual worlds, especially during the process of writing The Book Of Spirits which is the first publication of Kardec defining the bases of Spiritism.
One of the aged forms of communication, psychography, however, did not arise in Kardec's time. In the history of mankind are records of spiritual communication through writing in the oldest civilizations, although many of the mediums of the past were not aware of mediumship faculty itself, much less the origin of the content of their manuscripts.
Nonetheless it is from Kardec that this type of communication gains more force. In Brazil through the work of Francisco Cândido Xavier (Chico Xavier) with the most remarkable messages, many of them reproduced in the books signed by the medium. Not to mention the great original work written by Chico, composed of more than 400 psychographed books