About Sage Agastya and the incident with river Cauvery:
Sage Agastya was the great sage who laid down the grammar rules for the Tamil language. He was a very short person.
Once he was strolling along the banks of the river Cauvery. On seeing him, River Cauvery wondered how a great sage like him could be so short and started laughing at him.
Sage Agastya became very angry at the river Cauvery’s insult. He wanted to teach her a lesson, and so with his divine powers, he locked her up in his kamandal, the spouted pot in his hand.
A Sage who saw all this knew that the southern part of the country could not survive without river Cauvery. It was the life-giving river. He went to Mount Kailash to seek the help of Lord Ganesha to release river Cauvery from Sage Agastya’s kamanual.
Ganesha: Don’t worry. I will release river Cauvery from sage Agastya’s kamandal and I’ll do it as soon as possible.
Sage Agastya who locked up river Cauvery with his powers, was deeply meditating, with the kamandal by his side. Lord Ganesha took the form of a crow and reached the place where sage Agastya was meditating. He flew down low and toppled the kamandal, and released river Cauvery. He then changed himself into a small boy and stood in front of sage Agastya.
Sage Agastya: Hey boy, are you the one who released river Cauvery from my kamandal. I will knock you on your head. (Lord Ganesha changes his form) Your’s everlasting wisdom. I wanted to Knock your head without knowing that you had taken the form of a very small boy. Can you forgive me for my sin?
Sage Agastya, why did you stop hitting me, on my head? I would be proud to get knocked on my head by a great sage like you. Come knock me.
Agastya: Lord Ganesha, how can I do it? I should knock on my head for having tried to knock you.
Ganesha: Sage Agastya, you have not committed any mistake. From today, everybody who worships me in this manner would be blessed with wisdom, knowledge, and good virtues.