Lhe secret doctrine, synthesis of science, religion and philosophy is a book originally published in two volumes in 1888, a major work by Helena Petrovna Blavatsky. The entire work comprises six volumes. The first part of the work is the translation and commentary on an unknown book in an unknown language: the book of Dzyan. This part explains the origins of the universe, in terms derived from the Hindu concept of Yugas, ie by long periods of time through which the world is supposed to have evolved. The system is completed by a principle of "rounds", a sort of cosmic cycle or sequence of an evolution of the being, through various stages of existence, through which pass the earth, the solar system or the cosmos in their manifestation.
The second part of the book describes the origins of humanity through seven “root races” or “humanities”, dating back millions of years. The first root-race, the Chhâyâs, would be, according to Helena Blavatsky, "etheric" or "polar", and the second would have lived in Hyperborea. The third root race would have been that of Lemuria while the fourth, that of Atlantis.