Despite the Torah's explicit prohibition against divination (Deuteronomy 18:10-12), medieval Jews practiced it extensively—and spent centuries debating exactly where the line fell between forbidden sorcery and permitted "signs." The Talmud itself drew a distinction: Eliezer's test at the well (Genesis 24:14) and Jonathan's sign before battle (1 Samuel 14:9-10) were innocent, while deliberate omen-seeking was not. undefined Trachtenberg documented how this boundary was interpreted, stretched, and frequently crossed throughout the medieval period.
The most elaborate Jewish divination technique involved a child medium, a reflective surface, and a precise ritual script. A ritually pure child was seated—sometimes in the practitioner's lap—and mysterious words were whispered in the child's ear, which the child repeated aloud. The child then gazed into a polished surface (oil, a mirror, a thumbnail) and reported what appeared. First the child would see an angel. "What color is he wearing?" the master would ask. Red meant the angel was angry—more prayers were needed. White meant success. Then letters would appear, which the master would assemble into words and answers.
This ritual was remarkably stable across centuries and geographies. Rashi in 11th-century France mentions the requirement of a black-handled knife for invoking the "princes of the thumbnail." Manuscripts from 16th-century Spain, 17th-century Tunis, and 18th-century Ottoman lands preserve the identical detail. A 1455 German text by Johann Hartlieb describes an almost identical procedure—so close that it seems drawn from the same tradition, though scholars believe the accounts are independent.
Simpler methods flourished too. Sneezing was an omen—the Talmud noted its significance, and a late tradition held that before Jacob, everyone who sneezed immediately died. Dogs howling at night foretold death, a belief the Talmud (Bava Kamma 60b) connected to the presence of Samael, the Angel of Death, passing through town. Special foods eaten on Rosh Hashanah—apples in honey, pomegranates, fish heads—functioned as a form of sympathetic divination, where consuming symbols of abundance was believed to draw abundance into the coming year.
Even the great rationalist undefined Jaffe (16th century), who denounced most divination methods, stopped short of condemning all omens. The pull of tradition was simply too strong. Medieval Jews lived in a world where signs were everywhere—in flickering candles, in the flight of birds, in the itching of an eyebrow—and reading them felt less like sorcery than survival.