Gilgul—transmigration of souls גלגול נשמות
The teaching that a soul comes into the world more than once. It is not in the Talmud; Saadia Gaon is expressly against it; Kabbalah accepted and developed it. Three different answers, and all of them inside the tradition.
Two mistakes must be avoided here at once: not to present gilgul as the general teaching of Judaism, and not to declare it a foreign invention. Its history is the history of an argument.
What is absent. The Bible does not speak of transmigration, and neither does the Talmud. This is not reticence but absence: the subject is simply not raised.
The objection. Saadia Gaon, in Emunot ve-Deot, examines the opinion as someone else's and rejects it with arguments: a man's soul is human, and the notion that it enters the body of a beast he calls an absurdity.
The acceptance. Among the rishonim of Spain and Provence gilgul appears as a secret written of by hint: Ramban calls it "the secret of ibbur" and says that by it the book of Job is explained—why it goes ill with the righteous. The Zohar speaks openly. With the Ari it becomes a whole science: Chaim Vital set down the Shaar haGilgulim, where the roots of souls and their rectifications are laid out.
Why it was needed. Its purpose is single and intelligible: justice. If the account is closed within one life, the suffering of the righteous is inexplicable; if life is not one, the account is longer. Others answered the same question differently—by the world to come, or by refusing to explain. In this reference all the answers stand.
On the timeline
Related
Sources
Rishonim
- Saadia Gaon, Emunot ve-Deot, treatise six — the examination and rejection of the opinion of transmigration
Acharonim and later rabbinic literature
- Chaim Vital, Shaar haGilgulim — the Ari's teaching on the roots of souls and their rectifications
Basis: documents and evidence.