Four words arrive in succession, each one sealing the case. Aja — unborn. Nitya — eternal. Shashvata — changeless. Purana — ancient beyond reckoning. The soul was never born and will never die. It did not come into being at some point and will not cease at another. When the body is destroyed, the soul remains exactly as it always was.
The final line carries the full force of the teaching: 'na hanyate hanyamane sharire' — when the body is slain, the soul is not slain. Picture a clay lamp. The flame inside it burns. Break the lamp, and the fire does not break. It simply finds another vessel — or merges with the air. The container is fragile; what it holds is not.
This is among the Gita's most quoted shlokas, and with reason. Every fear of death, every grief over loss, every anxiety about the end of life meets its answer here. Not with consolation, but with a statement of fact about the nature of what we are.