Both Brihaspati and Sukra were Brahmins well versed in many fields of knowledge. However Sukra had mastered Sanjivni, the Science of reviving the dead through the use of Mantras (divine utterances). But this Science was not known to Brihaspati.
Sukra, by making use of the Sanjivini Mantra, was able to bring back to life the Asuras killed by the Devas, in the encounters. Since Brihaspati couldn’t revive the Devas killed in the battles, the population of the Devas was declining while that of the Asuras remained the same.
The Devas devised a plan to acquire the knowledge of Sanjivini from Sukra. They approached Kacha, the eldest son of Brihaspati and suggested to him that he become a disciple of Sukra, learn the Sanjivini Mantra in due course and then return to the kingdom of Devas to help them by reviving those killed by the Asuras.
Sukra was in the court of the Asura king Vrishaparva. Kacha went to him and introduced himself as the grandson of Angiras and the son of Brihaspati and requested him to accept him as his disciple. Sukra gladly agreed to his request.
Since Kacha was young and had knowledge of various musical instruments, he was able to please Devayani, Sukra’s daughter. He also gratified her by offering flowers, fruits etc. She began to develop a soft corner for him.
The Asuras becoming apprehensive that Kacha would learn the Sanjivini Mantra from Sukra, decided to kill him. They slew him when he was tending the cows of Sukra, cut him to pieces and fed him to the jackals and the wolves.
In the evening, the cows returned home, without Kacha leading them. Devayani, finding that Kacha had not returned, conveyed her apprehensions to her father. Sukra uttered the Sanjivini Mantra to bring Kacha back to life. Kacha emerged by tearing the bodies of the wolves and the jackals that had eaten his body parts. Prompted by his Guru, Kacha narrated what had happened to him.
On another occasion, Kacha was gathering flowers in a forest at the behest of Devayani. The Asuras killed him, pounded him into a paste and dispersed the paste into the waters of the ocean. Responding to the plea of Devayani, Sukra invoked the Sanjivini Mantra again. Kacha came alive rising from the waters of the ocean. Again, Sukra got appraised of what had happened to Kacha.
The Asuras did not stop with this second attempt. In their third attempt, they burnt Kacha and mixed his ashes in wine and offered the wine to Sukra, which he drank. When Devayani complained to her father about Kacha not returning home, Sukra said, “It seems Kacha has entered the region of the dead. I brought him to life twice but his life is being endangered again. He is not immortal. So, don’t grieve over his death.”
But Devayani was adamant and said that she would starve and follow Kacha.
Sukra then summoned Kacha to come alive. Kacha's voice was heard from Sukra's stomach. Sukra found out from Kacha how he had entered his stomach. He then told Devayani that the only way Kacha could come alive was by piercing his stomach and killing him in the process. Devayani replied that her father’s death would be as painful to her as Kacha’s death.
Sukra then told Kacha that he would teach him the Sanjivini Mantra so that Kacha could use it to bring him to life after coming out of his stomach. He then taught the Mantra to Kacha. Kacha came out of Sukra’s stomach by piercing it open. He then revived his Guru by invoking the Sanjivini Mantra he had just learnt.
Kacha told Sukra, “Since you have given me knowledge, you are to be considered as my father. Since I came out of your stomach, I have to regard you as my mother as well. If I cause any harm to you, I will be considered the most sinful of all persons.”
Sukra realized that because of his inebriated state, he had failed to detect that Kacha’s ashes were mixed in the drink given to him by the Asuras. He felt angry and pronounced, “From now onward, the wretched Brahmin who is unable to resist the temptation and gets drunk will be considered as having lost his virtue and will be hated by both the worlds.”
Kacha, after completing his studies, took leave of Sukra and returned to his abode, the Celestial kingdom.