The growth of New Souls depends upon two factors: merit and the passage of specific time segments; but the growth of Level Two souls that were included in Cain and Abel is not limited by a time factor and depends only upon merit.

Now we will explain an advantage of the second level over the first level. First level [souls] are unable to achieve NR"N all at once. If his deeds are worthy, at thirteen years he merits Ruach…

The next few sentences are not easy to comprehend, but the overall intention of the Rav can be clarified. The classical commentary on Gate of Reincarnations, Benei Aharon by R' Shimon Agassi, makes a parallel between the following teaching and what is taught in Etz Chaim (25:3). It is explained there that there are two different modes for the growth of Zeir Anpin. One depends upon the passage of specific time segments, and the other does not. In the same way we will see that the growth of Level One souls depends upon two factors: one is the merit of deeds, and the second is the passage of specific numbers of years. When he is born he gets a Nefesh, when he is thirteen he gets Ruach, etc. On the other hand, the growth of Second Level souls is not limited by the time factor. They can merit from Nefesh to Chaya at one time, independent of age, and that is their advantage over first level souls.

Although they [First Level souls] merit [by virtue of their deeds], it is only through the number of years [that they can achieve growth].

In other words, at birth a person merits Nefesh, and if his deeds are worthy, at thirteen years and one day he merits Ruach. When he reaches twenty years and there is sufficient merit, then the Neshama enters. This is the way it precedes until everything is completed.

Clearly, the growth of Level One souls depends upon two factors: merit and age. Level Two [souls]… are not dependent upon years but rather upon actions…

However, Level Two [souls] can achieve until the Nefesh of Atzilut even before the age of thirteen years and one day. When these sparks were included together within Cain and Abel, they were able to merit to all of the levels mentioned. Therefore, now as well, they are able to achieve all the levels fitting for them at one time. They are not dependent upon years but rather upon actions, including the meditation mentioned previously.

Second Level souls are not dependent upon the passage of specific time segments in order to achieve growth. The reason for this is that all the sparks of Level Two souls were included in Cain and Abel. At that time had Cain and Abel not sinned they could have grown all the way from Nefesh to Chaya. This potential became inherent in their sparks, even those that would be born later on.

However, the new souls of Level One are like those that have just been created. Their growth takes time. But once the paradigmatic pattern is established, then the passage of specific segments of time to develop is not a limitation, as the Rav has written in Etz Chaim (25:3, p.2:15a-b).

Know this rule. Whenever we are talking about the growth of Zeir Anpin needing time, we are talking about its first emanation. From then onwards, after it is emanated and set up, even though it receives new mochin every day as at first, it doesn't need to wait for [the passage of specific] time. In one instance it can be done, and not over long periods of time…

Therefore, new souls of Level One are dependent upon specific time segments. Level Two souls have already had the paradigmatic pattern set up. They do not need to wait for the passage of years. It appears that it is dependent upon the person's actions, and not his age…

Knowing this, we can now account for two different statements that seem to differ regarding the same issue. At the beginning of parashat Mishpatim (Zohar, 94b) it says, "Come and see. When a person is born, they give him a Nefesh... If he merits more, etc." It appears that it is dependent upon the person's actions, and not his age. This refers to Second Level souls that were included in Cain and Abel, and which are called "new" in some respect.

In Sabba of Mishpatim (Zohar, 98a), it seems that it is dependent upon one's age, as it says, "When he reaches thirteen years it is said about him, "…Today I have given birth to you ". (Psalms 2:7) Then they give him a Ruach. When he reaches his twentieth year, they give him a Neshama. Regarding this it says, "A son I was to my father…" (Prov. 4:3) This refers to Level One souls, which are completely new souls, and were never included in the soul of Adam.

[Commentary by Shabtai Teicher.]