A small boy was traveling in a boat along the coast when the prophet Elijah appeared to him. Elijah was famous for wandering the world in disguise, testing Jews, delivering messages to the worthy. He had chosen the child for a piece of secret business.
Elijah showed him a vision of the stones of carbuncles, the glowing red gems that would one day line the walls of the rebuilt Jerusalem (Isaiah 54:12). He let the boy see them gleaming in their heavenly storehouse. But the vision came with a condition. You must show these stones, Elijah said, to Rabbi Joshua ben Levi in the town of Lud. Only to him. Promise me.
The boy promised. Elijah vanished. And as soon as the prophet was gone, the stones themselves became physically present in the boy's hands. He had the carbuncles of the future Jerusalem in his lap on a boat.
He made his way to Lud and sought out Rabbi Joshua ben Levi, one of the greatest amoraim of the third century CE, a man who according to legend had already bargained with the angel of death. The boy brought out the stones and showed them. Rabbi Joshua saw them. The vision was delivered.
Then the boy set off for home. Three miles outside Lud, something went wrong. Perhaps the boy had grown proud of the treasure in his bag, perhaps he lingered too long showing them to others, perhaps the condition of the gift was that they were only ever his for a single moment. The stones slipped from his hands, rolled down the road, and fell into a cavern. The ground closed over them. They disappeared.
This enigmatic story from tractate Bava Batra 75a, preserved in The Exempla of the Rabbis (Gaster, 1924), is a classic Elijah tale. A vision of redemption is shown to the right sage through the hands of a child, and then the proof is taken back into the earth, to wait for the true day.