Indra others complained to Vishnu Maheswara against the atrocities committed by Mahishasura. Vishnu and Iswara personified their respective powers Vaishnavi and Maheswari. The power of Indra came out as Indri, Brahmani came out of Brahma. Kaumari came out of Skanda (Subrahmanya Swamy). All these powers fused into one great power which became known to the world DURGA which literally means "one who can not be approached". Everyone then prayed to the great power Durga to destroy Mahishasura.
But Mahishasura had many powerful assistants who needed to be destroyed before their chief could be attacked. All the gods then presented to the goddess their own weapons. Vishnu gave her a chakra, Indra gave vajra, Siva gave her a trident (trishula), Yama gave her a sword and armour and Prajapathi gave her akshamala. Himavan, father of Parvathi, gave her a lion which became her vehicle thereafter.
In her fight against Mahisha the Devi first destroyed Sumbha, Nisumbha, Raktabeeja and such other formidable generals. In the course of the war the Mother assumed many forms. These are known as Navadurgas and are described in Devikavacham as follows: Sailaputri, Brahmacharini, Chandraghanta, Kushmanda, Skandamata, Katyayani, Kalaratri, Mahagowri and Siddhidhatri. She become Mahakali in the battle against Raktabeeja. Mother Durga ultimately destroyed Mahishasura and restored to Indra his domain.
Philosophers evolved an allegorical meaning to this legend first described in Durgasaptasati within the Markandeya Purana, composed by sage Vyasa. Indra represents the mind of human beings. Mahisha represents the animal passions within the humans. Sadasiva is the sublime philosophy of universal love and Vishnu is the protector. Mother Durga is the noble inner nature of man. After the animal passions are subdued and controlled what remains is peace. Durga sapta sati is recited every day for nine days during the Devi Nava Ratri / Dussera celebrations.
In the 36th chapter of Brahmanda Purana, Sage Vyasa describes the popular panegyric (Stotram) recited by devotees as Lalitha Sahasranamam. This was taught by Hayagreeva (vishnu) to sage Agasthya. It was composed by Vagdevi and was known to the Devas. Sage Agasthya taught this to Manu, the first man. This stotra is also called SRI VIDYA, knowledge of the ultimate powers controlling the universe. The contents of Sri Vidya were presented in a more elaborate detail by Sankaracharya in his Soundaryalahari, a composition of one hundred verses. The rejoicing manifested in Durga festivals is symbolic of people's desires to overcome base qualities and establish the rule of virtue. Worship of God as Mother Durga is a very popular form of worship all over India. It is great unifying force bringing together different communities and different parts of India.