Tikun for the Nefesh is accomplished through the performance of positive mitzvot, and blemish of the Nefesh is caused by transgression, but for the Ruach the emphasis is on occupation with the Torah and its study.
We will now explain rectification and blemish in detail. We will begin with the rectification of Nefesh, that is from the world of Asiya, which is the lowest of all of them and enters into a person first at the time of birth.
You already know that no higher portion can enter until the lower part completes its tikun. First, all the parts of the Nefesh, that is from Asiya, must enter and complete their tikun. Afterwards, the parts of the Ruach, that is from Yetzira, can begin to enter within him. When they are completed, then the Neshama, that is from Beriya, will begin to enter until everything is finished.
However, there are conditions and distinctions concerning all this as will be explained in this, the eighth gate, called the Gate of Reincarnations.
It seems that this general introduction ought to appear at the beginning of the book! However, keep in mind what Reb Shmuel the son of Rabbi Chaim Vital, the editor and redactor of the Eight Gates, wrote in the beginning of this chapter. This chapter is a sort of abridgement of the entire subject of gilgulim. Therefore, it makes sense that this introduction appears here.
Occupation with Torah acquires Ruach….
Nevertheless, it is also worthwhile to keep in mind an important rule concerning all Torah knowledge. Subjects, descriptions and stories of the Torah are not necessarily presented in a chronological order. Events that occur at a later time may very well appear before the presentation of other events or descriptions that precede them. Similarly, sometimes what you need to know first to understand the "beginning" will not appear until later. This is because the Torah is an open or "infinite system" (if such a combination of words is permissible).
The tikun of a person who merits to the Nefesh of Asiya is through the performance of positive mitzvot whose number is 248.
Blemish is a result of [positive mitzvot] that were not fulfilled, or because of transgression of one of the 365 negative mitzvot.
Blemish caused by one of the positive mitzvot that was not fulfilled, applies when both the opportunity and the obligation were present, but he transgressed and did not do what was incumbent upon him to do. In the next section the Ari will discuss mitzvot where the opportunity or obligation were not present.
Occupation with Torah acquires Ruach that is from Yetzira, as will be explained.
This statement is somewhat problematic, and needs to be understood by broadening our conceptual categories. The Benei Aharon (11:31) has also pointed this out. For example, if occupation with Torah alone rectifies Ruach, then a person who is working on his Ruach should be exempt from the active performance of all the other mitzvot!?
To answer this problem consider the following. It is the teaching of the Ari in Etz Chaim 40:2, but the words quoted are those of the Benei Aharon (ibid.).
All practical mitzvot (like tzitzit, tefillin, eating matzah, sukkah, etc.) rectify the External (Partzuf). Mitzvot that are performed through speech, such as prayer and occupation with Torah, rectify the Internal (partzuf).
The External Partzuf is a partzuf just like the Internal Partzuf. It, too, has Vessels and Light, or mochin. The two are equivalent and parallel. The only difference between them is one is external and the other is internal. Relative to each other they are equivalent to Nefesh (External) and Ruach (Internal) relative to each other.
Thus, on every level there are the External and Internal aspects, or what can be called the Nefesh and Ruach of that level. The Nefesh/External partzuf of any level is rectified by the performance of practical mitzvot, whereas the Ruach/Internal partzuf is rectified by the mitzvot pertaining to speech and thought.
[Commentary by Shabtai Teicher.]