Āstīka (Astika) is the son born of the womb of Jaratkāru(Jaratkaru) — sister of the Nāga(Naga; Snake) Vāsuki (Vasuki), sired by Sage Jaratkāru (so Āstīka’s parents bear the same name). Sage Āstīka was born in order to save the Nāga community from the Sarpasatra of Janamejaya –and he was able to save the snakes indeed. The story of his birth is very interesting, too.
When Uccaiḥśravā came out of th ocean during Samudramanthana (Churning of the ocean), Kadrū asked Vinatā, “What is the colour of Uccaiḥśravā?” Vintā said it was white. But Kadrū said that the horse was white but its tail was black. Kadrū then gave a condition. If Vinatā̍s answer proved to be true, Kadrū would be at her service. And if Kadrū̍s conjecture was right, Vinatā would be her slave. After this condition was set, even knowing that Vinatā had been right, Kadrū took resort to deception. She asked her snake-sons to hang around the tail of Uccaiḥśravā, so that it appeared black. But some of the snakes did not agree to be part of this deception, so the mother Kadrū cursed them, “You will be burnt to death in the Sapayajña of Janamejaya.”
Hearing the matter of Kadrū, Vāsuki, king of the snakes, got very much concerned for the oncoming danger that would befall his kins. The gods also felt sympathetic for the cursed snakes and along with Vāsuki, they also went to Brahmā, to seek a remedy for the calamity. Brahmā said, a learned sage and ascetic called Jaratkaru, belonging to the clan of sage Yāyāvara, who had so far been a celibate, would marry as per the the instrucion of his forefathers, only for the purpose of continuing the line. He would marry a princess who would be his namesake. And their son will save the snakes from thr Sarpasatra of Janamejaya.” Hearing the words of Brahmā, another snake-chieftain, Elāpatra told Vāsuki, “You have a sister called Jaratkāru. When sage Jaratkāru will seek a girl to marry him, you should let her marry the sage, for the sake of the snake-clan”. So Vāsuki took great care of her sister.
One day, sage Jaratkāru found his forefathers inside a deep chasm, with heads downward and legs upward. Jaratkāru asked who they were and the reason for this strange posture. He learned from them, since he had been engaged in a reclusive life and hard asceticism, he had not been attentive to the need of marriage and procreation. So their genealogical line is going to be discontinued, and the forefathers are hanging painfully like sinners, they are gradually going down to naraka (the hell).
Sage Jaratkāru then disclosed his identity and the forefathers asked him to get married. Jaratkāru said, “I shall marry a woman who will be my namesake, and for whose care and protection, I won̍t have to take any responsibility”.
Then Jaratkāru traveled in several places, but could not find a girl suitable for his conditions. He felt sad, thinking of the degenerating state of his forefathers, and entered a forest. He said to himself– I need a girl for marriage. At that time, Vāsuki appeared there, along with his sister. Sage Jaratkāru married goddess Jaratkāru, under the previously set conditions.
Some days after the marriage, sage Jaratkāru left his wife and went away. Immediately after the marriage, he said to his wife, “If you anything which is not pleasing to me, or say anything unpleasant, I will leave you and your home. One day sage Jaratkāru was sleeping, resting his head on the lap of his wife. And the evening-time was drawing near. Goddess Jaratkāru was afraid, if her husband continued to sleep, he would fail to perform the sandhyā-vandanā, and that would be an act of adharma. On the other hand, he was tired and so sleeping, he would be angry if he was woke up. Considering all aspects, finally goddess Jaratkāru considered maintaining the dharma of her husband with more importance, and trike d to wake him. Getting angry, Jaratkāru said, “You have shown disrespect to me, thus waking me up from my sleep. I will not live with you any more.” Goddess Jaratkāru felt sad and concerned for her relatives. Jaratkāru assured her saying that, there remains a great, righteous and learned sage inside her womb.
Pointing to the boy in the womb, his father Jaratkāru said, Jaratkāru said, ̍asti̍, so that boy came to be known as Āstīka. He was very intelligent from his childhood. He learned Veda from Pramati, son of Cyavana, belonging to the line of Bhṛgu. He was brought up in the house of Vāsuki, and his father̍s line was also free of danger because of him.
Āstīka also gave comfort to his mother̍s clan. Knowing that Parīkṣit has been dead by the biting of Takṣak, Janamejaya decided to take revenge upon him, and the whole clan of snakes. He performed Sapasatra, and in the fire, snakes started falling one by one. Vāsuki told his sister Jarakāru, “Though your son is a boy, he is intelligent and learned, Let him protect me and my relatives.” Jaratkāru told Āstīka about the curse of Kadrū, and the story of the birth of Āstīka, as the redeemer of the snake-clan. Goddess Jaratkāru said to Āstīka, “Vāsuki gave me away to your father̍s hand, that will not go in vain, if you try. Āstīka assured his mother and maternal uncle Vāsuki, and went away to stop the yajña of Janamejaya.
Now before the yajña commenced, one vāstukāra told king Janamejaya, no unknown brāmaṇa should be allowed to enter the yajña-place, so that there might not be any cause of detriment to the yajña. Hearing this, Janamejaya also gave strict orders so that the guards would not let anyone enter without his permission. When Āstīka tried to enter the yajña-place, naturally the guards stopped him. Āstīka, the started singing praise of the king Janamejaya, all the sages, priests present there. Everybody was pleased to hear that. Janamejaya said, “Though being a boy, he speaks like an experienced and aged man. So in my consideration, he is not a boy, but an aged person. ”
King Janamejaya expressed the wish to grant a boon to Āstīka. At that time, Caṇḍabhārgava, the hotā of the yajña, said– Takṣaka has not yet fallen in the fire, so you cannot grant a boon in this situation. Takṣaka was hiding inside the uppergarment of Indra. As Janamejaya requested the priest to call him to fall in fire, the priest started performing homa, calling to Takṣka. By the power of the mantra, Takṣka slipped from Indra̍s hand and began to come down to the earth. Considering that Takṣaka was sure to fall in the fire of the yajña, then Janamejaya wanted to grant his promised boon to Āstīka. Āstīa also thought, it was the perfect time for asking for the boon.
He prayed to Janamejaya so that the yajña could be stopped, and no other snake would fall in the fire. Janamejaya repeatedly asked him to request for another boon. While they were thus conversing, Takṣaka was remaining in the sky. Seeing this surprising matter, Janamejaya requested his priests to stop the yajña. Granting the boon to Āstīka, Janamejaya was also pleased. He proposed to Āstīka to participate in his Aśvamedha yajña. Āstīka felt honoured at this, and since the sarpasatra was stopped, he was successful and returned to his maternal uncle̍s house, in good spirits.
Other snakes, too, pleased with Āstīka, showered blessings on him. All of them said to Āstīka, “What desire of yours can we fulfil?” Sage Āstīka then said, “those who will listen to the narrative of this righetous act of mine, let them be free of danger from snakes.” This righteous Āstīka freed the snakes from the Sarpasatra of Janamejaya, created a lineage in due course, and received nirvāṇa through tapasyā.
In Devībhāgavatapurāṇa, it has been said that once Āstīka met his father, sage Jaratkāru. At that time Jaratkāru gave him Sarasvatī mantra on the bank of Kṣīroda sāgara.