The Gemara ascribes great significance to dreams, but it recognizes that they are influenced by conscious and psychological stimuli. Thus we find that when challenged to predict the dreams of non-Jews, the Sages were able to suggest scenarios that were curious enough to get them to ponder them for an entire day, which led them to dream about them at night. The Gemara relates:
The Roman emperor said to Rabbi Yehoshua, son of Rabbi Ḥananya: You Jews say that you are extremely wise. If that is so, tell me what I will see in my dream. Rabbi Yehoshua said to him: You will see the Persians capture you, and enslave you, and force you to herd unclean animals with a golden staff. He thought the entire day about the images described to him by Rabbi Yehoshua and that night he saw it in his dream. Shevor Malka, king of Persia said to Shmuel: You Jews say that you are extremely wise. If that is so, tell me what I will see in my dream. Shmuel said to him: You will see the Romans come and take you into captivity and force you to grind date pits in mills of gold. He thought the entire day about the images described to him by Shmuel, and that night he saw it in his dream.
Shevor Malka – Shahpuhr – was the name of a number of Persian kings. Our Gemara is referring to the first king Shahpuhr, who continued his father’s success in wars against the Roman Empire, capturing the city of Netzivim and arriving at the border of Syria. In the course of a number of attacks, he not only defeated the Roman emperor Velrinus, but he captured him and held him until his death. With regard to internal matters, he was an open-minded leader, and allowed a good deal of freedom of religion. It appears that he showed an interest in Judaism and was on good terms with the amora Shmuel.