Rabbi Yochanan was teaching his students on the verse, “I will make thy windows of agates, and thy gates of carbuncles” (Isaiah 54:12). He said, “The Holy One, blessed be He, will bring precious stones and pearls — each one thirty cubits by thirty — and will polish them down to twenty by ten, and set them in the gates of the future Jerusalem.”
A student in the back rolled his eyes. “No one has ever seen a pearl larger than a small bird’s egg,” he muttered. “Are we to believe such giants exist?”
Some weeks later, the student sailed on a trading voyage. Far out at sea, his ship passed a strange place where he saw figures beneath the waves — angels, as it seemed to him, quarrying stones of unearthly size and polishing them with tools of light. He called down to ask what they were for. “For the gates of Jerusalem,” a voice answered.
When the student came home, he went straight to Rabbi Yochanan’s house and fell at his feet. “Master, you were right. I saw them with my own eyes.”
Yochanan looked at him for a long moment and said, “Scoundrel. If you had not seen, would you not have believed? You have insulted the words of the sages.” And he fixed his eyes on him, and the student turned to a heap of bones.
The rabbis told the story to warn against contempt: the future is larger than the doubter’s imagination, and the measure of a disciple is whether he can trust what his teacher has not yet proved.