Sanjivani (saṃjīvanī)

The Sanjivani is the science of reviving the dead, held exclusively by Shukracharya, teacher of the asuras, which is why their armies could fight forever while the gods' dead stayed dead. The gods send the young Kacha to learn it as a student, and he is killed three times and finally fed to his teacher in a drink before Shukracharya, forced to teach him from inside his own body, gives up the secret. The story sits at the head of the Yayati cycle and supplies the epic with its first lesson in how knowledge changes hands.