Mārkaṇḍeya was a sage who had, through extreme tapas, won the boon of immortality. He would not die. He would not be touched by the dissolution of the world.
At the end of a kalpa — a cosmic age — the world dissolved, as it always does. The earth burned. The oceans boiled. The mountains crumbled. The gods withdrew. Finally nothing was left but water — a single endless ocean, dark, silent, covering everything. This is called the pralaya.
Mārkaṇḍeya, alone among living beings, was still alive. He drifted on the ocean, bewildered. Everything he knew was gone. He had no reference point. The sky was gone. The earth was gone. There was only the water.
He drifted for what felt like endless time. He wept. He called for help. No one answered.
Then he saw, in the distance, a banyan leaf floating on the water. On the leaf, a child was lying, peacefully asleep.
Mārkaṇḍeya approached. The child opened his mouth, slightly, in his sleep. And Mārkaṇḍeya was drawn, somehow, into the child's mouth.
Inside the child, he saw everything. The earth, the mountains, the oceans — not the dissolved ones, but the ones that had once been. The cities he had known. The sages he had studied with. The rivers, the trees. All of it was there, intact, inside the child. He saw himself in there too — a small figure walking among the scenes, as if he had never left.
He wandered inside for a long time, realising that the entire universe had been inside this child all along. That the child was not holding it. The child was what the universe was inside of.
Then he was back outside, on the ocean. The child smiled at him. Do you know who I am, the child asked.
Mārkaṇḍeya said — you are Nārāyaṇa, the one who rests on the waters when everything else has gone.
Yes, said the child. I breathe out, and a universe arises. I breathe in, and it dissolves. You have seen a full breath of mine. You are the only one who has. You will tell others, when the universe comes back.
The child closed his eyes again and slept. The ocean began to stir. A new universe began to form. Mārkaṇḍeya, now witness to a secret almost no one else held, rejoined the world.
The story is the Purāṇic image of the cosmic cycle. Its philosophical claim is simple and enormous: the universe is not the final thing. There is something prior to the universe, on which the universe rests, in which the universe dissolves. The child on the leaf is an image of that. The breath is the cycle. We are, in our entirety, inside one in-breath.
To remember this occasionally — that we are breath inside breath inside a larger breath — is the whole use of the story. It does not require belief. It requires only imagination, and sometimes that is the same thing.