The story
The day is Murugan's. One telling makes it his birth, another the day Pārvatī gave him the spear with which he ended Sūrapadma, and the second is the one the processions act out.
Thai is the month of new beginnings in the Tamil reckoning — Thai piṛandāl vaḻi piṛakkum, when Thai is born a way is born — and Pūṣya is the star of nourishment. The festival sits where the two meet.
What the day is actually known for is the kāvaḍi: an arched wooden or metal frame carried on the shoulders up the hill to the temple, decorated with peacock feathers, sometimes with pots of milk hung from it, sometimes attached to the carrier with hooks and skewers. It is carried in fulfilment of a vow, and the carrier walks in a trance to drumming, usually after a month of fasting and celibacy.
