The Dybbuk is the first comprehensive study of the historical and kabbalistic sources of the dybbuk phenomenon, from the first recorded case of dybbuk possession in Safed in 1571 onward. Dybbuk possession differs from possession by demons or Satan. Its origin is in the Kabbalistic concept of gilgul (transmigration) for sins that are so grievous that Gehenna is not sufficient punishment, and the soul must therefore wander until...