A woman came to Rabbi Eliezer with a dream. She described what she had seen in the night. Rabbi Eliezer listened carefully and said: "You will bear a male child." In time, the woman gave birth to a son. The dream had said what he told her it had said.
The story might have ended there, as a simple account of a sage's gift for pesher chalomot — the interpretation of dreams. But the tradition preserved by Gaster's Exempla (no. 219, 1924) continues, and the continuation is what unsettles.
On another occasion, Rabbi Eliezer's own students were asked to interpret a dream in his absence. They gave a negative interpretation. And the dream fulfilled itself exactly as they had said.
This echoes the Talmud's teaching in Berakhot 55b: All dreams follow the mouth — kol ha-chalomot holkhin achar ha-peh. A dream is not a fixed decree of the future. It is a possibility, a latent script. The act of interpretation partly writes what the dream becomes. Tell a dream one way, and it goes that way. Tell it another way, and it goes another.
This is why the rabbis taught that a troubling dream should be narrated only to people who love you. Why dreams should, where possible, be turned to good. Why an anxious dreamer should say, "I have seen a good dream," even when he has not — because the saying shapes the seeing.
The dream is not the future. The interpretation is.