The tandava of Lord Shiva causes the downfall of Apasmara. The epileptic creature, personification of avidya (roughly translates to ignorance), lies powerless beneath the feet of the dancing Mahadeva, symbolic of the predominance of satyam (the eternal truth or wisdom). Also, the presence of Lord Shiva - with the creative Damru and the destructive flame in His posterior hands, in the centre of an aureole of a ring of flames - inspires the devotee with love and shraddha for the Lord (Shivam).
Finally, the aesthetics (sundaram) of this one-of-a-kind iconography is unparalleled in art anywhere in the world. From the mudra of His limbs and the curvaceous snakes wound around His body, the lateral prominences balance the long, lissome physique of the Lord. The flaying locks and a crown of multiple-hooded snakes frame the handsomely carved countenance. Note how the traditional multi-tiered pedestal adds balance to the Nataraja composition.