Ātman

Ātman (devanāgarī: आत्मन्) is a Sanskrit word that means "self". In Hindu philosophy, especially in the Vedanta school, it refers to one's true self beyond phenomena.

H. P. Blavatsky regarded ātman as a universal principle, rather than a human one:

Spirit (in the sense of the Absolute, and therefore, indivisible ALL), or Atma. As this can neither be located nor limited in philosophy, being simply that which IS in Eternity, and which cannot be absent from even the tiniest geometrical or mathematical point of the universe of matter or substance, it ought not to be called, in truth, a “human” principle at all.

Ātman is frequently called the "higher self" in human beings. However, this does not mean that each person has his or her own higher self. In reality, there is only One self:

Atma, the "Higher Self," is neither your Spirit nor mine, but like sunlight shines on all. It is the universally diffused "divine principle," and is inseparable from its one and absolute Meta-Spirit, as the sunbeam is inseparable from sunlight.

Further reading

• Ātman at Theosopedia