Maha Sashthi is the sixth day of Devi Paksha during Durga Puja. It is marked as the formal beginning of Durga Puja in West Bengal. In West Bengal and other Eastern part of India four rituals- Kalparamvo, the beginning of the Pujas, Bodhan, the consecration of Ma Durga"s idol, Amantran, inviting the Goddess and Adhivas, sanctifying the stay of the Goddess in the puja area of the pandals and the zamindari pujas. These are performed on Maha Sasthi of Devi Paksha, according to The Bengali and Hindu calendar.

Mythology on Maha Sashti
In Treta Yuga, before beginning of his onslaught on Lanka, Lord Rama performed Durga Puja in autumn season to defeat Ravana. This is the time of Dakhshinayana- Sun`s Southward journeys and according to Puranas, Gods sleep during this time. So Rama had to first wake up the Goddess Durga. On this day he began his premature awakening or Akal Bodhan of Goddess Durga.

Mythology on Maha Sashti in Bengal
The Bengali community believe that on the day of Sasthi Uma or Goddess Durga, who is identified with Goddess Parvati the divine consort of Lord Shiva or Mahadeva comes to home of her father from her husband place with her four children- Lord Ganesha, Lord Kartika, Goddess Lakshmi and Goddess Saraswati. The Bengali folks participate in the setting up of the Durga Ghat before the idol on Sasthi. They are formally welcoming Uma, the daughter of King Daksha as a daughter on her arrival for three day trip to his father"s house.

Kalparambha in Maha Sashti
The day of Kalparambha is also known as the day of "Akal Bodhon" which means untimely invocation of Goddess Durga. Traditionally Goddess Durga was worshipped during Chaitra month. Even now Goddess Durga is also worshipped for nine days during Chaitra month and this period is known as Chaitra Navaratri. However with time Chaitra Navratri has become less significant compare to Sharada Navratri. Kalparambha during Durga Puja is symbolically same as Ghatasthapana or Kalashsthapana which is done on the Pratipada Tithi of Navratri. The three days Durga Puja in West Bengal is smaller version of nine days Navaratri which is mostly followed in other states of India.

Rituals in Maha Sashti
The "Bodhon" is ritual include the unveiling of the face of the idol. Bodhon, Amontron and Adibas are the important rituals of Maha Sasthi apart from Kalparambho.

Celebration of Navaratri
In other parts of India especially in Maharashtra, Gujarat, Rajasthan, the sixth day of Navaratri is celebrated as Durga Sasthi or Maha Sasthi. On the eve of Sashti, the Katyani Puja is observed as part of Nava Durga Puja in Shaktheya Samprdaya.

The rituals of Kalparambha are equivalent to Bilva Nimantran in other states. On the very same day, Goddess Durga is invited to dwell in Bilva tree or in a Kalash. The act of inviting Goddess Durga is known as Amantran and dwelling her spirit into Bilva tree is known as Adhivas. The best time to perform invocation of Goddess Durga is Sanyakal which is the time window of approximately 2 hours and 24 minutes before sunset.