It's likely you're referring to J.Z. Knight, a self-proclaimed psychic and spiritual teacher who claims to be channeling an ancient warrior named Ramtha.
Ramtha, according to Knight, is a 35,000-year-old warrior from Atlantis who has been channeled through Knight since 1982.
Ramtha has been the subject of multiple books, including:
* Ramtha: The White Book: A collection of Knight's channeled teachings and spiritual insights attributed to Ramtha.
* Ramtha: The Blue Book: Another book containing channeled teachings and spiritual insights attributed to Ramtha.
* Ramtha: The Red Book: A book containing the channeled teachings of Ramtha on specific topics.
* Ramtha: The Yellow Book: A book containing Ramtha's teachings on various aspects of life and spirituality.
Please note: Ramtha is not a recognized figure in mainstream academia or spirituality, and his teachings are considered by many to be pseudoscience and New Age philosophy.