Medieval Jewish belief held that the dead do not simply vanish. As SAFE0 Trachtenberg documented, the spirits of the deceased remained active, aware, and dangerously close—capable of helping the living, harming them, or simply refusing to leave.
The theological foundation was the concept of multiple souls. Drawing on Kabbalistic teaching elaborated in texts like Hochmat HaNefesh (the vital soul), medieval Jews understood that a person possesses several spiritual components—the <i>nefesh</i>, <i>ruach</i>, and <i>neshamah (the higher soul)</i>—which separate at death. While the higher soul ascends, the lower soul lingers near the body, especially during the first year. This is one reason Jews visit graves: the dead are literally there, and they can hear.
The Sefer Hasidim is filled with ghost encounters. Judah the Pious reportedly communicated with the dead regularly, and stories circulated of spirits who returned to warn family members, complete unfinished business, or protest improper burial. The scholar Israel Bruna recorded cases of the dead appearing in dreams to deliver messages. Glückel of Hameln, in her famous 17th-century memoirs, described ghostly visitations as ordinary events.
The practice of cemetery visitation on fast days and before Rosh Hashanah (the Jewish New Year) and Yom Kippur (the Day of Atonement) had explicit supernatural logic. Worshippers went to the graves to recruit the dead as intercessors—to ask deceased <i>tzaddikim (a righteous person)</i> (righteous ones) to plead their case before God's heavenly court. The Maharil and other medieval authorities endorsed this practice, and it generated a rich body of liturgy recited at gravesides.
Among the strangest proofs offered for the survival of the spirit after death was this one, cited in the Ziyuni on the authority of "non-Jewish scholars": dice carved from the bones of a corpse will win a man as much wealth as he wishes. The dead, it seems, retained a kind of power—and that power could be harnessed.