"The man who is...pure
contains the Universe
in the pocket of his heart."
-Black Elk, a holy man of the Oglala Sioux
Wakan Tanka is the name for "The Great Spirit" in the Sioux tradition. However, its meaning is closer to "Great Mystery", and is typically understood as the power or the sacredness which resides in everything. Wakan Tanka pervades the entire universe, transcending even the gods -
something similar in nature to the Brahman of Hinduism, or the Tao of Lao Tse.
During a vision, in which he found himself looking from the prospect of a mountain top, Black Elk saw the extent of the power of this Universal Being. Self-realisation is the experience of this Universal Being, not of an illusory individualism. It is a process which first requires humility. In egocentric societies, the notion of humility is associated with weakness. To Black Elk, humility is the key to the infinite and invincible strength of Wakan Tanka.
"[The Sun Dancers] also put rabbit skins on their arms and legs, for the rabbit represents humility, because he is quiet and soft and not self-asserting — a quality which we must all possess when we go to the center of the world. This center which is here, but which we know is really everywhere, is Wakan-Tanka."