The Hebrew word <i>mazal</i> (מזל) originally meant "constellation" or "star." Only gradually did it shift to mean "luck"—and the journey of that word tells the story of Jewish astrology itself. As Elias Levita noted in his 16th-century lexicon, "We call good fortune good mazal and the reverse bad mazal—in German it is Glück and in Italian ventura." undefined Trachtenberg traced how astrology permeated medieval Jewish life despite fierce opposition from some of the tradition's greatest minds.
Maimonides rejected astrology categorically. undefined of Tachau attacked Jews who "busy themselves with astrology and believe in it and make it their creed, and thereby bring harm to others." But they were fighting against the tide. The Talmud itself (Shabbat 156a-b) records debates about whether Israel is subject to stellar influence, and the weight of popular practice came down firmly on the side of the stars. undefined ibn Ezra composed major astrological works. Abraham bar Hiya HaNassi wrote the Megillat HaMegaleh, an astrological-messianic treatise. The Beraita de Mazalot, an astrological text attributed to ancient authorities, circulated widely and was heavily borrowed by Sefer Raziel.
Each planet had its own archangel, and each person was born under the governance of a specific star with its attending angel. The zodiac signs were mapped onto cities and countries—the Nehmad veNa'im lists which lands fell under which celestial sign. Days of the week carried astrological weight: Monday was considered unlucky for beginning new ventures, echoing a German proverb that "What one begins on Monday won't last a week."
The most dramatic astrological belief concerned the Tekufah—the solstices and equinoxes. At these moments, the cosmic balance shifted, and water became poisonous. Jews across medieval Europe covered or discarded all stored water during the Tekufah, a practice endorsed by major authorities and codified in the Shulhan Arukh. Some placed a piece of iron in their water vessels as protection. The Kabbalistic explanation was remarkable: the Hebrew letters of <i>barzel</i> (iron, ברזל) are the initials of Jacob's four wives—Bilhah, Rachel, Zilpah, and Leah—and these matriarchs protected the water against spirits.
The practice was so entrenched that the Ziyuni records Jews in many communities calling the Tekufah "Wasserkalb"—and drinking during the Tekufah was believed to cause dropsy. Astrology was not abstract theory. It shaped when people married, when they traveled, and when they drank water.