(The S in this name is pronounced like 's' in 'so', TH like 'th' in 'with' and the consonant Y like 'y' in 'you'.)
There seem to be two people with this name. One Agasthya, son of Pulasthya, was of very early times of creation.
The second Agashtha of whom we know more and who was very famous too, was born from the divine damsel Oorvashi throug the pair of gods Mithra and Varuna, when they both tempted themselves for the damsel and their semen spilled out into a pot, wherefrom agasthya was born.
Agasthya was avery great sage. His wife was Lopaamudra, princess of Vidarbha kingdom. Agasthya's disciple was Agnivesha or Agniveshya who was preceptor of Drona in archery.
Agasthya was known for his penitential powers. Many stories tell about his great powers.
1.) Once, mount Vindhya wanted to surpass mount Meru ans it began to grow higher and higher. It grew so high that it hindered the path of the Sun in the sky thereby disturbing the time cycle itself. All the gods prayed to sage Agasthya to subdue Vindhya. He went from north to south and reached Vindhya which stood touching the sky. Agasthya asked the mountain, 'My wife is not able cross you if you stand that tall. Please reduce to ground level for her safe and easy passage over you. And be so until we return and cross you. Later, you may grow again.' Vindhya obeyed his words out of fear of being cursed if went otherwise. Agasthya and his followers crossed the mountain and settled in the south itself without returning to north. Vindhya remained low, as he promised to remain so until Agasthya's return which did not happen at all.
2.) Once all the gods went to Agasthya and prayed to him to do a favor to them by drinking all the water of the ocean so as to expose the immumerable demons taking shelter beneath it. He simply sipped off the entire quantity of the water in the ocean, taking it into his palm. After the gods killed the vulnerable demons, they asked him to release the water to fill the sea again, as the ocean is the abode of many aquatic beings and it should not therefore be dry. But agasthya replied that whatever he drank was digested then itself and re-issuing of water was not possible. The great ocean remained dry untill Bhageeratha filled it with the waters of Ganga, many thousands of years later.
3.) Once there were two demon brothers , Vaathaapi and Ilvala. They plotted to kill the sgaes in the forests and devised a plan. Vaathaapi would assume the form of a goat and Ilvala would cook his meat as food and call sages for dinnner. After the innocent sages ate the food, Ilvala would call Vaathaapi to come out. Vaathaapi comes out ripping open the stomuch of the sage, killing him. After many sages were killed, the other sages went to Agasthya and prayed to him to free them from the trouble of the demon duo. Agasthya went to the demons like a normal sage. As usual, Ilvala did his part of the plan and served the food to Agasthya. When Ilvala called out his brother, Agasthya simply said that the moment he ate him, Vaathaaapi was digested fully and that he would never return. Ilvala remained silent and afraid. He too was burnt into ashes by Agasthya. Even today, while referring to a heavy eater or a notable embezzlement, people jocularly use (though in a corrupted tounge), as the words uttered by Agasthya after eating Vaathapi's meat as 'Jeernam jeernam Vaathaapi Jeernam' (The correct words should be 'Jeerno jeerno Vaathaapirjeernah', meaning 'Digested. Digested. Vaathaapi was digested off.'.
4.) Once in the heaven, Indra was to forego his status as ruler of the three worlds, due to some sin on his part. The gods and sages picked a king Nahusha and installed as Indra as a makeshift arrangement. But unforeseen status made Nahusha arrogant and he bacame rude to Indra's wife Shachi. He even employed the sages to carry his sedan. Agasthya was one of the sages that carried the sedan. As he could not walk faster, Nahusha kicked him on the head and shouted, 'sarpa! sarpa!' (move! move!). Agasthya became infuriated at his unseemly behaviour and cursed him to become a serpent in the deep forests for many thousands of years ('Sarpa' also means'snake'.). Thus he saved Indra and the gods from a big trouble.
4. ) In Raamaayanam too, Agasthya is mentioned. When Raama was tired and he was unable to kill Raavana as quickly as he thought, Agasthya went to him and told sme exultations about the Sun god (It is named 'Aadithya-hridayam'.) which even today many devotees recite for health, victory and safety. By the way, a sage in Raamaayanam itself was referred to as Agasthya's brother. Raama met the sage and paid respects to him. But, the sage's true name was not mentioned. Even today, people jocularly refer to certain persons as Agasthya-Bhraatha ie Agasthya's brother implying that their original merits did not ever surface but they are reckoned great since they are linked to wellknown personalities.
5.) In ashvamedha parva, his sacrifice is described. When Indra did not rain during the twelve-year course of the sacrifice, the participating sages were worried. But agasthya assured them of obtaining everything needded by assuming the status of Indra himself. However, Indra was wise and rained thoroughly until the sage's sacrifice ended normally.
He is mentioned in many puraanams. He is considered to be the inventor of the script, grammar and
thesaurus of the ancient Thamil language. Even today, an astrological prediction system after his name is in vougue, named Agasthya Naadi, wherein the right thumb impression of a person is taken and depending on its features, his horoscope is read out from a palm leaf book out of many thousands of them.
"After praying to Naaraayana, Nara, Sarasvathi and Vyaasa, then one should read the Jayam."
DEDICATED TO MY DEAR NIECE VYSHNAVI KRISHNA