Vayas, key term for “age” in the ayurvedic treatises, is a heuristic concept that is helpful in reflecting on issues of longevity, rejuvenation, and immortality. When considering longevity specifically, the Chāndogya Upaniṣad III.15-16 provides extensive material for reflection. In the context of ritual invocations aiming at longevity, it offers a meaning of vayas close to that found in medical treatises; it describes three periods of life, and provides us with a canonical human lifespan of 116 years.
