Bhahvrucha Upanishad

It is classified as one of the eight Shakta Upanishads and attached to the Rigveda. The Upanishad is notable for asserting that the Self (soul, Atman) is a Goddess who alone existed before the creation of the universe. She is the supreme power, asserts the text, she is the ultimate reality (Brahman), from her being and because of her the universe was born, she is the knowledge, the consciousness and the soul (Atman) of every being. The philosophical premises of Bahvricha Upanishad assert the feminine as non different, non-dual (Advaita) from transcendent reality, she being the primary and the material cause of all existence, and the text belongs to the Shaktadavaitavada tradition (literally, the path of non-dualistic Shakti).