Reprinted from The Jewish Religion: A Companion, published by Oxford University Press.
The Bible expresses the belief that dreams can contain revelations from on high, as in the dreams of Jacob, Joseph, and Pharaoh in the book of Genesis. The prophetic vision, the Bible states (Numbers 12:6), comes in a dream. A rabbinic saying has it that a dream is a sixtieth of prophecy. Maimonides (Guide of the Perplexed, 3.36-8) develops his theory that in the dream the imaginative faculty is awakened, without which prophecy is impossible.
There is a good deal of material on dreams in the Talmud but a degree of ambiguity about the efficacy of dreams. In one talmudic passage it is implied that dreams are a manifestation of the unconscious, as Freud suggests, or, at least, this is the meaning that can be given to the talmudic statement: “A man is only shown in a dream that of which he thinks during the day.”
Legal Status of Dreams
In matters of law, information obtained in a dream is disregarded. The illustration is given of a man whose father appeared to him in a dream and informed him that a sum of money, hidden in such-and-such a place had been designated by him for charity and it belonged to the poor. The ruling given was that the dream could be disregarded and the son could keep the money for himself.
While a rabbinic scholar might occasionally claim that a suggested interpretation of a biblical or talmudic text came to him in a dream, the habit of Jacob of Marvege (13th century) of using information conveyed to him in dreams as authoritative in law was extremely unusual.
After fasting and employing other techniques, Jacob would present halakhic (Jewish legal) queries to heaven, to which he received replies in dreams. These replies are recorded in Jacob’s work entitled Responsa from Heaven. We should not be surprised that, according to the work, ‘Heaven’ always had the same halakhic opinions as the French talmudists.
Interpretation & Fasting
The talmudic statement that a dream depends on how it is interpreted, puzzling to the more philosophically minded, is discussed in the Responsa of Solomon Ibn Adret. Based on a talmudic passage, a special ceremony developed of interpreting for good a bad dream. The procedure was for the man who had the dream to say to three other persons: “I have had a dream and do not know what to make of it”; and they would reply: “The dream is a good one and is for your good.”
Many people, disturbed by a bad dream, would fast in order to ward off the possible evil effects. The rabbis allowed such a fast to be undertaken even on the Sabbath in order to release the man from his anxiety but they required him to undertake another fast for having fasted on the Sabbath.