Gargi Vachaknavi (born about 9th to 7th century BCE) was an ancient Indian philosopher. In Vedic literature, she is honored as a great natural philosopher, renowned expounder of the Vedas, and known as Brahmavadini, a person with knowledge of Brahma Vidya. In the Sixth and the eighth Brahmana of Brihadaranyaka Upanishad, her name is prominent as she participates in the brahmayajna, a philosophic debate organized by King Janaka of Videha and she challenges the sage Yajnavalkya with perplexing questions on the issue of atman (soul). She is also said to have written many hymns in the Rigveda. She remained a celibate all her life and was held in veneration by the conventional Hindus.