Surprise! Reincarnation is an ancient, mainstream belief in Judaism. The Zohar, written by Rabbi Shimon bar Yochai close to two thousand years ago, speaks frequently and at length about reincarnation. Onkelos, a righteous convert and authoritative commentator of the same period, explained the verse, "Let Reuben live and not die" (Deuteronomy 33:6) to mean that Reuben should merit the World-to-Come directly, and not have to die again as result of being reincarnated. The great Torah scholar, commentator and kabbalist, Nachmanides (Ramban 1195-1270), attributed Job's suffering to reincarnation as hinted in Job's saying "God does all these things twice or three times with a man, to bring back his soul from the pit to the light of the living" (Job 33:29,30).
Rabbi Chaim Vital, the disciple of the Arizal (1534-1572), explains in detail the Jewish concept of reincarnation. The soul is placed in a body in order for a person to attain spiritual perfection by refraining from transgression and performing mitzvot. If one accrues too much spiritual damage, the soul must return to repair the damage. Similarly, if one didn't take full advantage of the opportunity to perfect the soul, it may be reincarnated to complete its perfection. The way it works is as follows:
The first time a soul enters this world, the person is able to perfect the three lower levels of soul, nefesh, ruach, and neshama. If so, the soul goes to "the world of souls" where it awaits resurrection. If not, the different levels of soul can only be perfected in different lifetimes. Each time a level of soul is perfected, the person dies, is reincarnated, and given the chance to perfect the next level of soul. Previously perfected levels of soul are not damaged by sins in the current reincarnation. The soul continues to be perfected in this way until it is perfected at least in nefesh, ruach, and neshama, at which point the soul goes to "the world of souls". The bodies of all the soul's reincarnations will be resurrected, but the first body is the main one.
Another reason souls may be reincarnated is for zivug (soul-mates): Either because they missed their zivug, and perfection can only be achieved through marrying one's soul-mate; or even if they married but one soul wasn't perfected, the other must return to be with its zivug. Sometimes even a perfected soul, such as that of a tzaddik (a very righteous person), may be reincarnated in order to help perfect others. While a person is not aware of previous reincarnations, the Arizal explained that those areas of Torah that a person particularly enjoys learning are those that weren't completed in previous lives and should be concentrated on now. Conversely, the mitzvot that one finds particularly difficult are specifically those needing correction.
The majority of kabbalists are of the opinion that in addition to the first life, there are at most three incarnations. They cite the above-mentioned verse from Job "twice or three times with a man". The Zohar says this on the verse "punishing the iniquity to the third and fourth generation [reckoning from the first life]" (Ex. 34:7).
However, Sefer HaBahir says that a soul can be reincarnated a thousand times. The renowned kabbalist of the 1600's, Rabbi Menashe ben Israel, resolves this contradiction by saying that since the purpose of reincarnation is to perfect the soul, after three times with no progress the soul loses its chance ("three strikes and you're out").
But if the soul is progressing, even in small increments, it can be reincarnated many times. Another resolution is that the soul can be reincarnated as a human only three times, as suggested by the verse "twice or three times with a man". Afterwards the soul may be reincarnated even a thousand times as a lower life form.
The following story illustrates how past wron
