For example, "if the year begins in Aries," the text starts, "the year will be lean. Its four-legged animals will die.... Grain will lack height, but rye will reach good height and ripen. The Nile will overflow copiously. The king of the Romans will not remain in one place.... The heavenly stars will be dispersed like sparks [a meteor shower?] and the moon will be eclipsed. The first grain will die, but the last grain will be harvestable. Produce will be diseased starting at Passover...."
Similarly, "if the year begins in Leo, there will be spring rains.... At the end of the year there will be a lot of rain."
Starting with Aries — a particularly bad year, as we just saw — the text works its way through the zodiac counterclockwise to Capricorn, predicting increasing prosperity for each successive symbol.
By including rain as part of what the zodiac controls, the author defiantly breaks with tradition. After all, Deuteronomy 11:13-17 promises rain only to those who obey God's commandments, and warns of no rain to those who stray. That passage is so central that it forms part of the text that Jews to this day keep written on entrance-ways in a religious marker called a m'zuzah.
Similarly, chapter 2 of the Book of Daniel may mock astrologers. And in the New Testament, Acts 7:42-43 condemns star worship. Other ancient material, like Enoch and Jubilees, likewise implicitly or explicitly rejects astrology.
But astrology in Judaism and Christianity has long been controversial.
For instance, a passage in the Talmud (Shabbat 156a) speaks out against astrology, but also seems to recognize the power of the stars. When a mosaic portraying the zodiac was discovered in Bet Alfa at an ancient (mid-first millennium AD) synagogue, some scholars saw a reflection of the importance of astrology to Judaism, while others sought other explanations, or, at least, tried to stress the hundreds of years that separated the mosaic from the days of the Bible.
Christian tradition is similarly conflicted, but it has a more thorny problem to address. Matthew 2:1-12 seems to connect Jesus's birth with astrology in the form of a star that guides the "wise men" (magi, perhaps astrologers) to Jesus. This possibility was so threatening that St. Augustine in the 5th century AD spoke out against any astrological power of the stars: "The star didn't cause the wonders of Christ's birth, but Christ caused the appearance of the star."
Is the Treatise of Shem just the work of a misguided astrologist, or does it preserve a tradition that some people would prefer to erase?