In this section the Arizal will disclose new information concerning the concept of ibur, which he has already discussed in Chapter One (see Section 5). First, however, he will review the important rule that we have been studying in this chapter: namely, if a Nefesh achieves tikun only in a subsequent gilgul and not in its first lifetime, then it cannot receive Ruach in the same gilgul. The person must first die, and then his Nefesh and Ruach will be reincarnated together.
If a Nefesh reincarnates and becomes rectified through its actions to the point that it is ready for its Ruach, he cannot receive his Ruach, as it has been explained. [If it is not his very first gilgul, then] two or three levels of soul cannot become unified in one gilgul without great need, as we will mention later. Rather, each one requires its own gilgul.
Only in the first gilgul can the Nefesh, Ruach, and Neshama be rectified within one body
First the Nefesh needs to be rectified, and even when this happens he will not receive his Ruach until after he dies. Then the Nefesh can reincarnate and merit the Ruach. The same is true of the two of them; if they become rectified to the point that they are ready for their Neshama, they cannot receive it until they reincarnate again. Then they can merit their Neshama.
As we have already learned, only in the first gilgul can the Nefesh, Ruach, and Neshama be rectified within one body. After that, the person must reincarnate to move from level to level, even if he finishes one level "early."
What happens for the Nefesh that is already rectified but lacks a Ruach?
We are talking about after the first gilgul, when it is not possible to receive another level of his soul without reincarnation. What happens, though, in the meantime until reincarnation, if the Nefesh is already rectified?
This is the sod ["secret"]: From the same level of purity and extent of tikun attained by this Nefesh, there will reincarnate into the body of this person, while he is still alive, the Nefesh of a righteous tzadik that has already completed gilgulim and rectification, and does not need to reincarnate here. By entering here, the Nefesh of this tzadik takes the place of the Ruach of this person.
A regular gilgul involves reincarnation from one lifetime to another.
Thus, from the time that the Nefesh has become rectified, the Nefesh of a righteous person will enter him and fill the role of the Ruach that cannot come down.
Sometimes, it is even possible for the souls of early tzadikim, such as the Nefesh of our patriarch Abraham, or similar souls, to reincarnate. This depends upon the tikun and purification of the Nefesh of the person.
Gilgulim [of this type] which occur during the lifetime of a person are called by the rabbis, "sod ["secret of"] ibur." And this is the basic difference between a regular gilgul and an ibur.
According to what we have learned here, a regular gilgul involves reincarnation from one lifetime to another. Ibur, on the other hand, is the "impregnation" of a person by the soul of a rectified, righteous tzadik because the Nefesh has completed its tikun, but it cannot receive Ruach without reincarnating since the tikun did not take place in its very first gilgul.
[Commentary by Shabtai Teicher.]