It is important to know that the impact of one's sin is dependent upon the level of his soul. Thus, someone whose Nefesh is from the malchut of Atzilut will cause a blemish in that level and to his soul root there. This is the case for the rest of the levels as well.

However, if a person in a previous gilgul had a Nefesh and Ruach from Asiya and Yetzira and then sinned and blemished his Ruach, this would necessitate reincarnation into a second person. Even if only the Nefesh returned into this [second] person, when he sins he blemishes Yetzira, as if he had also received the level of Ruach.

In his previous gilgul he blemished both Nefesh and Ruach. Only Nefesh reincarnates. Nevertheless, if he sins in the new gilgul, it will also blemish Yetzira, as if he had also received Ruach. Because he had Ruach in a previous gilgul he can blemish it again in his current gilgul, even though he currently only has his Nefesh.

Also, when he (the second person) wants to do teshuva, he must perform a tikun as if he had a blemished Nefesh and Ruach.

He only has a blemished Nefesh, but he must repair the damage as if he had both Nefesh and Ruach, even though a blemished Nefesh and Ruach cannot reincarnate together. Regarding teshuva, it is necessary to know the manner of one's gilgulim

Also regarding teshuva, it is necessary to know the manner of one's gilgulim, which we will briefly explain now based upon what we have discussed in another place.

This is a continuation of the subject of teshuva, which was discussed in the last section.

Suppose that a person, for example, reincarnated twenty to thirty times beforehand. He will need to know if the first ones had NR'N from BY'A, and if he blemished them. If that is the case, then all the subsequent thirty, even if the Nefesh alone entered each one, will have to rectify as if they blemished all of BY'A, since the first one that preceded all of them was a Nefesh that received light from the Neshama of Beriya. Thus, to complete his teshuva he will have to return the light that it [his soul] had in the beginning.

Although Nefesh only is reincarnating in the current gilgul, he must rectify all three levels of the soul. This is because all three levels of the soul were blemished together in the first gilgulim. The reason for this is that the Nefesh received light from the higher levels when they reincarnated together. Rectification of the Nefesh includes rectification of the higher lights that had become part of her existence. And those higher lights belong to Ruach and Neshama.

Furthermore, this phenomenon has very important implications for some of the things that we observe in this world.

This is the esoteric meaning of the verse, "…For she has taken from the hand of G‑d double for all her sins." (Isaiah 40:2). One cannot grasp such matters, but he must trust that all G‑d does is righteous …

Sometimes a person will commit a (relatively) light sin, but they will be very strict and very exacting with him, punishing him as if he committed a severe sin, "twice" what he did. Thus, one cannot fully fathom the ways of G‑d when he sees someone experiencing this. One cannot grasp such matters, but he must trust that all G‑d does is righteous and with justice.

It seems that he is getting a double punishment, something completely disproportionate relative to the sin, but it is because he is being punished for the blemishes caused by his sin in the higher worlds of Yetzira and Beriya as well.

When one who does not have this special knowledge about the roots of gilgulim sees a case of retribution that is apparently inordinate relative to the sin, he may begin to doubt, G‑d forbid, the justice of the divine system of reward and punishment. Therefore, "he must trust that all G‑d does is righteous and with justice."

However, suppose from the first [gilgul] through the ninth of the thirty he only merited a Nefesh and a Ruach, but for the tenth [gilgul] he merited a Neshama; he then sinned and blemished it. Any sins that resulted during the first nine blemished the Ruach, and even more so, the Nefesh. However, regarding the tenth and all those after it, through the thirtieth, the blemish and tikun will also affect the Neshama. Based upon this, you should be able to figure out any other case.

A person cannot do complete teshuva…until he knows his Soul-Root…

Thus, we find that a person cannot do complete teshuva as it should be done until he knows his Soul-Root and the levels of gilgulim of his soul that preceded him. The Zohar, when discussing the verse, "Tell me, you whom my soul loves" (Song of Songs 1:7) is adamant about this. It discusses there at length that a person needs to know the identity of his soul, why it has come into this world, and what it needs to rectify.

Obviously, this requires knowledge beyond the normal. See for example, Kol Hatur, "Remizin Kadishin."

[Commentary by Shabtai Teicher.]