In Judaism, different attitudes have been expressed towards astrology. Most Talmudic sages believed in the decisive role played by celestial bodies in determining human affairs. It was possible, they thought, for astrologers to predict the future by consulting the stars but also for them to err in understanding the contents of their forecasts. According to the Talmud, everyone has a particular star (mazal) which is his patron. (Shabbat 53) Mazal - מזל does not mean luck. The word comes from נוזל - Nozel, which means the heavenly flow of each person.

A number of Rabbis held the view that the power, which stars had over ordinary mortals, did not extend to Israel. Thus, Rabbi Yochanan said: "Israel is immune from the flow and of the "influence" of the constellations. (Shabbat 156a: ein mazal le-yisrael). On the other hand, Rava said: "Length of days, children, and finances do depend upon destiny" (mazal; Moed Katan 28a).

Why do the stars form an important link in the chain of G-d's Providence over the world? G-d's Providence works through angels, but the angels work through the stars because the angels are like souls to the stars. The Abrabanel in Devorim 18 explains that just like the human soul needs a body to accomplish its mission in the world, so too angels need a body to accomplish their mission. Thus, each star is actually a body of an angel. But why are the angels and stars necessary in the link between G-d and man? To test us, does the angel or star have its own independent power, which is classic idolatry – עובדת כוכבים or are they merely a tool of G-d, like a hammer in the hand of a carpenter. When the carpenter builds you a cabinet, do you thank him or his hammer? Our task is to distinguish between the Creator and his creations, which include astrology.

The only scholar to reject astrology completely was Rambam (1135-1204) who regarded it as a vain superstition unworthy of being called a science. Asked by the rabbis of southern France whether it was possible to combine the theories of astrology with the principles of Judaism, he replied that astrology was no science at all and that it behooves us never to engage in it. Of Rava's statement, quoted above that it's all about mazel, he says: "It is possible that it was said only as a momentary ruling because of a particular circumstance at that time." He found astrology to be forbidden by the Torah in the command: "You shall not observe these times" (Leviticus 19:26 lo te'onenu; Hilchot Akkum 11:9), and criticized the Jews of antiquity for their superstitious faith in astrology, thereby bringing upon themselves the destruction of the Temple and exile.

Astrology has to some extent penetrated even the Shulchan Aruch. One explanation of the custom of fasting on the anniversary of a parent's death (yahrtzeit) is that on that day the destiny or fate of the child is bad (re'a mazlei; Ba'er Hetev to Yoreh De'ah 402:12). It was also the custom in some communities to prepare a bed and table in a mother's room on the eve of her son's circumcision so that the child should enjoy good mazel (Be'er Hetev ibid. 178:3). A Jew should try to postpone litigation with a non-Jew in the inauspicious early part of the month Av (Orach Chayyim 551:1).

A vestige of astrology remains even today. The fact that mazal means "constellation", "planet", "fate", or "destiny", does not inhibit us on joyful occasions in individual and family life from wishing fellow Jews mazal tov, which means may you merit a good heavenly flow.