Mirra Alfassa (21 February 1878 – 17 November 1973), also known as The Mother, was the spiritual collaborator of Sri Aurobindo.
She came to Sri Aurobindo's spiritual retreat on 29 March 1914 in Pondicherry, India. Having to leave Pondicherry during World War I, she spent most of her time in Japan where she met the Nobel laureate poet Rabindranath Tagore. Finally she returned to Pondicherry and settled there in 1920. After 24 November 1926, when Sri Aurobindo retired into seclusion, she founded his ashram (Sri Aurobindo Ashram), with a handful of disciples living around the Master. She became the spiritual guide of the community.
The experiences of the last thirty years of Mother's life were captured in the 13-volume work The Agenda. In those years she attempted the physical transformation of her body in order to become what she felt was the first of a new type of human individual by opening to the Supramental Truth Consciousness, a new power of spirit that Sri Aurobindo had allegedly discovered. Sri Aurobindo considered her an incarnation of the Mother Divine and called her by that name: The Mother. When asked why he called her the Mother, Sri Aurobindo wrote a seminal book The Mother by introduction to the Mother's outstanding Personalities,portions and embodiments of her divinity. That's how she came be known as The Mother.