Ancient Roman astrologers connected each day of the week with a heavenly body; hence Saturn corresponds to Saturday and was associated with the Jews, for whom the seventh day was holy. In Hebrew, as in English, the association is acknowledged in the planet’s name: Shabb’tai. Shlomo Sela explains the symbolic implications of this link:
Greek and Arab astrology . . . considered Saturn to be the most malignant of the seven “planets” [a category that included the sun and moon]; and thus the Jews, astrologically governed by Saturn, were considered to be contaminated by the planet’s wicked nature.
Abraham Ibn Ezra (ca.1089–1161) is the first Jewish thinker to deal with the problematic link among Saturn, Saturday, and the Jews. He addresses the astrological association throughout his writings, both scientific and nonscientific. He removes the sting of this embarrassing linkage by stressing that Saturn is actually conducive to a Jew’s religious faith. In his long commentary on Exodus 20:13, Ibn Ezra associates Saturn with the fourth commandment—“remember the Sabbath day and keep it holy”—and explains that this correspondence allows the Jews, by not occupying themselves with everyday matters but devoting themselves solely to the fear of God on this day, to protect themselves from Saturn’s baneful influence and also to improve the quality of their religious belief.