Manasa is a goddess of snakes, the sister of the King of the Nagas, Sesha (sometimes Vasuki). She is also known as Nagesvari, Bisahari, Janguli and Padmavati. She is gnerally depicted as an auspicious devi, of fair complexion, wearing red, flanked by snakes, and with a swan for her vehicle. Her husband is Jaratkaru, and her son, Astika. Manasa is also referred to as the daughter of Shiva.
Manasa is traditionally worshipped (particularly in Bengal) by offering milk and bananas at the foot of trees or in an earthenware pot. It is widely believed that worshipping Manasa will keep people safe from snakebites, whilst disrespecting her brings catastrophe – usually in the form of the disrespectful person being killed by a snake. She also has the power to cure diseases such as smallpox, and grants wealth & prosperity to her devotees.
During the monsoon season, pots filled with milk are placed in the kitchens of rural homes so that stray snakes can drink the milk and (hopefully) will go away without harming people.
The above link is a modern retelling of the Manasamangal – an epic Bengali poetic tradition related to Manasa which emerged from the 13th century onwards. It is part of a wider poetic tradition known as Mangalkavya – “poems of well-being” which describe the greatness of a particular Bengali deity and were traditionally rendered as musical plays.
A more recent story attesting to the power of Manasa concerns the Bengali historian Dineshchandra Sen (1866-1939). Sen spent the early years of his career compiling Bengali folktales and publishing them as evidence of India’s cultural obstacles to the process of modernisation. Sen, it is said, was particularly scathing about Manasa. Shortly after the publication of his 1896 book Bengali Language and Literature Sen became depressed, which culminated in a dream of an endless procession of snakes entering his bedchamber whilst a voice accused him of disloyalty to the goddess. On awakening, Sen smelled a fragrance that he took as a sign of the goddess’ presence. He deleted the Manasa-critical section of his book and recovered from his depression within three days. Sen made a public statement in which he interpreted the royalties from his book as a gift from the goddess.
June McDaniel (2003) provides an instance of how a devotee is ‘called’ by the goddess:
“I interviewed a tribal Santal trance medium, Parvati Soren, who would get possessed by the snake goddess Manasa. As a child she had visions of snakes, which would lead her to other worlds. Later she got a severe fever, and she was ill and near death, and had a vision of the goddess. The goddess called her to be her devotee, and Parvati got well when she agreed to be medium and priestess for the goddess. She understood this to be a spiritual illness, with the dream command given by the goddess. Manasa demanded worship, and gave Parvati matted hair or jata to show her religious status. She became a married healer, respected by the village as an important religious figure. As a tribal woman following a folk Hindu deity, she would not have high status, but her role as a holy woman had caste Hindus coming to her for blessings. In many rural areas of India, possession trance is the highest union.”
My Mother, Myself: Female Mystical Identity in Bengali Shaktism, 2003