“Occasionally even the mystical illumination produced by the effluence of the divine power from one sefirah to another is designated as sod ha-‘ibbur. In general, the kabbalists of Gerona restricted the transmigration of souls, on the basis of Job 33:29, to three rebirths following the first entry of the soul into the human body, though they admitted the existence of exceptional cases.
An important detail has been transmitted from the school of Nahmanides. In the famous disputation with the ex-Jew Paulus Christiani, the monk invokes the well-known aggadah according to which the Messiah was born at the hour of the destruction of the Temple.
To this Nahmanides replied: “Either this aggadah is not true, or else it has another explanation according to the mysteries of the sages.” Although the wording of this reply clearly points to kabbalistic teaching, it has not been understood until now.
Nahmanides does indeed give a plausible—literal and exoteric—explanation of the aggadah, to the effect that the Messiah was currently biding his time in the terrestrial paradise, but his true opinion can be gleaned from the questions of his disciple Shesheth des Mercadell concerning metempsychosis, where this aggadah figures as a proof text for this doctrine.
What the aggadah means to say is, therefore, that since the destruction of the Temple the soul of the Messiah is in the process of ‘ibbur. On this point, Nahmanides and his school depart from the older idea of the Bahir section 126, according to which the soul of the Messiah does not inhabit a human body before.
On the other hand, this text already exhibits the transition to the doctrine, first attested shortly after Nahmanides, to the effect that the name of Adam is an abbreviation (ADaM) of the three forms of existence of this soul in Adam, David, and the Messiah.
This would imply that the Messiah has to pass through various stages of incarnation so that his essence “always lives among us” in one form or another. The idea that also arose shortly after Nahmanides and according to which “soul sparks” can fly off from a central soul and thus pass simultaneously through many bodies is not yet attested in Gerona.
This doctrine was also used in the school of Solomon ibn Adreth in order to eliminate the difficulty that would arise at the resurrection of the dead for the different bodies through which one single soul had passed. The different bodies of the resurrected would be inhabited by sparks of the same soul, thus providing a solution to the problem.
According to Azriel there also exist souls of such exalted rank that they do not return to the world of bodies, but remain in the “world of life” and thus do not participate at all, or only in a purely spiritual sense, in the resurrection.
In this manner the kabbalists seem to move, at least as regards a privileged category of superior souls, in the direction of a denial of bodily resurrection—precisely the view for which the radical Maimonideans were so bitterly rebuked. It should be added, however, that this idea appears only in strictly esoteric contexts describing the eschatological progress of the souls after their departure from the terrestrial world and was never formulated in a dogmatic manner.”
Gershom Scholem, Origins of the Kabbalah, pp. 459-60.