Avani Avittam
According to puranas, two demons, Madhu and Kaitabha, stole the Vedas from Lord Brahma. Heeding to the pleas of his devotees, Lord Narayana assumed the form of a humanoid with horse like face, known as Lord Hayagriva, destroyed the demons and restored the Vedas to Brahma. This event happened on the Pournami day of Shravana month and hence the day is considered very auspicious for starting to learn the Vedas or any other art or craft.
The time-honoured ritual of changing the sacred thread (Poonal) commonly known as Aavani Avittam, falling in the Tamil month of Avani, under the star Avittam, is also observed by certain sects. Generations of men come together to observe this auspicious ceremony, chanting relevant slokas. It falls on Pournami day of Shravana month for those who follow Yajur Veda. Followers of Rig, Sama and Atharvana Vedas observe the same ritual on different days. Regardless of when one observes Avani Avittam, the aim is to pray for knowledge, wisdom and the blessings of Lord Narayana.
Avani Avittam, apart from marking Hayagriva’s appearance, is also observed as Satyanarayana Vratham across many parts of the country.