Seth is an energy personality essence that channeled through Jane Roberts during the 1960's and 70's. A considerable number of books have been published that describe Seth's message from the the Other Side. These messages are quite profound and focuses significantly on probable realities.
Books:
The Unknown Reality (volume I & II) by Jane Roberts [ISBN
0-13-938779-X] & [ISBN 0- 13-938852-4] (Prentice-Hall)