Bhagwan Shiv has many forms through which the energy of life moves in the Universe. He is the creator of the first sound and rhythm in the Universe and the greatest exponent of the gandharva vidyas which are the arts of dance and music. As he likes music and dance, the prayers offered to him through the arts are very dear to him. His Incarnation as Nataraj, the God of dance is an interesting story.
Once in the forest of Thillai, there dwelled a group of Rishis who did not practise their austerities and led a life involved in pleasure and desire. Bhgawan Vishnu and Bhagwan Shiv decided to teach them a lesson and get them back into the correct path of Dharma. Bhagwan Shiv disguised as a handsome young bramhin and Bhagwan Vishnu took the form of Mohini and both went to the forest to the ashrams of the Rishis. The sages got attracted to Mohini, while their wives to the young brahmin. As the wives of the Rishis got attracted to the Brahmin, this made the rishis jealous and angry. Out of their arrogance and pride of their powers, they wanted to punish Lord Shiva.
They created a sacrificial fire and performed a Yagn from which a huge tiger emerged. Bhagwan Shiv with simple ease killed the tiger and adorned its skin around his waist as his clothing. Then, a Trishul came to hurt him, but Bhagwan Shiv held it firmly and it became his weapon. Then an antelope emerged, but Bhagwan Shiv caught hold of it in his left hand. Then a great snake emerged, which Bhagwan Shiv garlanded around his neck. A Damaru next emerged with deafening sound, but Bhagwan Shiv clasped it in his hand and played it in tune as a musical instrument. Finally, a dwarf sized demon, Mulyaka emerged, but Shiva took hold him and pressed him under his foot. This demon is the arrogance and pride which are destroyed under the divine feet of Bhagwan Shiv. Then, he began to dance with great energy and it was the first dance in the Universe. The movements were heroic, full of energy and hence came to be known as Tandav. (Tandu, in Sanskrit means to hit with energy).
All gods witnessed this cosmic dance and their joy was out of bounds and praised Bhagwan Shiv as the God of Dance, thus naming him Nataraj. After witnessing this divine dance of Bhagwan Shiv, the Rshis realised their mistake and sought forgiveness of Bhagwan Shiv. The compassionate Shiv ji forgave their mistakes and thus they all left their luxury life and sought the true enlightening through worship and faith in Bhagwan Shiv. As the God of dance, he bestows happiness and prosperity to all who worship him through this divine art.