We learned that at the moment of the sin itself there is no difference between one aveirah and another, since every sin severs a person from the Holy One, blessed be He. After the fact, however, there is a difference: when a person transgresses a sin that does not carry kares, the blemish that is created is a smaller one.
The gloss printed alongside the chapter:
"ולפי ערך וחלוקי בחינת הפגם בנפש ובשרשה בעליונים, כך הם חלוקי בחינת המירוק והעונש בגיהנם או בעולם הזה" - "and according to the measure and the various categories of the blemish in the soul and in its root above, so too are the various categories of the cleansing and the punishment, whether in Gehinnom or in this world." Every sin blemishes in a different way, and therefore the process of cleansing differs from sin to sin, even though all sins alike sever.
This explains why the order of punishments contains distinctions: lighter punishments and more severe ones, punishments in this world and punishments in Gehinnom. These differences stem from the fact that the blemish produced by each sin is different, and consequently the cleansing process is different as well - "לכל עון וחטא עונש מיוחד למרק ולהעביר הלכלוך והפגם," "for every iniquity and sin there is a particular punishment, to scour away and remove the soiling and the blemish." For it is well known that none of the punishments in the Torah are, G-d forbid, vengeance, as though the Holy One, blessed be He, were looking to settle accounts with the Jew who sinned. They are nothing but a cleansing and a scouring: the punishment is already the healing of the problem, not the problem itself.
"וכן בחייבי מיתה וכרת אין פוגמים כולם בשוה" - "and likewise among those liable to death and kares, they do not all blemish equally." Even within the category of sins that carry kares, not all are the same. Hence one must distinguish between the severance and the blemish: the severance is equally present in all of them, while the blemish differs from sin to sin.
Let us return to the language of the chapter. After the sin, in a transgression that does not carry kares, since the Jew is in any case the Holy One's only son, he has indeed been severed, but the blemish is not so powerful, and therefore he is restored immediately: "הרי גם נפשו החיונית הבהמית המלובשת בגופו וכן גופו חוזרים ועולים מהסטרא אחרא וקליפה זו ומתקרבים לקדושת נפש האלקית שבו המלובשת בהם, המאמינה בה' אחד" - "then even his vital animal soul, clothed in his body, and likewise his body, return and rise up out of the sitra achra and that kelipah, and draw close to the holiness of the divine soul within him that is clothed in them, which believes in the one G-d."
At the moment of the sin the nefesh habahamis was sunk in the depths of the kelipos and cut off from the Holy One, and the divine soul was dragged down there along with it. But since no great blemish was created, a person can emerge from there immediately, because the divine soul remained in its holiness and in its faith in the Creator, and nothing in its essence was damaged. If there was any blemish and soiling in it, it was only on an external layer: in his essence the Jew remained a believer even at the moment of the sin.
In the words of the chapter: "שגם בשעת החטא הייתה באמנה אתו יתברך" - "for even at the time of the sin it was faithful to Him, may He be blessed" (an expression borrowed from Megillas Esther). The divine soul stands always in complete bond and faith; "רק שהיתה בבחינת גלות ממש" - "it was only in a state of actual exile." At the moment of the sin it goes down into exile and is dragged against its will into the depths of the kelipos, into the animal soul of the sitra achra, which causes the body to sin and drags it down with it into the depths of she'ol, lower and lower - and even in that very hour, while it is in the depths of the kelipos, it remains faithful to Him, may He be blessed.
This is along the lines of the well known formulation of the Rambam in Hilchos Gerushin: even a Jew who cries out that he does not want to do G-d's will, deep within him one can uncover that he does in fact want to. Even when he says "I do not want," he wants. For a Jew there is no true severance in his essence.
Nevertheless, at the moment of the sin his fall is a real fall: he has fallen under the impurity of the sitra achra and the kelipah of avodah zarah, may G-d protect us, "ואין לך גלות גדול מזה, מאיגרא רמא כו'" - "and there is no greater exile than this, from a lofty roof..." into a deep pit. True, since the sin is not severe in its blemish he has the power to return quickly, but this does not mean that there are transgressions in which no severance takes place: as far as the severance goes, it exists in every single one.
"וכמו שנתבאר לעיל" - "as was explained above." The root of the matter is explained in chapter 2 of Tanya: "דשרש ומקור נפשות כל בית ישראל הוא מחכמה עילאה, והוא יתברך וחכמתו אחד וכו'" - "for the root and source of the souls of the entire house of Israel is from the supernal chochmah, and He, may He be blessed, and His wisdom are one." For this reason the divine soul is always bound to its source and cannot be blemished, and as we mentioned earlier: on the level of "a Jew, even though he has sinned, is a Jew," even kares does not sever.
"והוא כמשל האוחז בראשו של מלך ומורידו למטה וטומן פניו בתוך בית הכסא מלא צואה, שאין לך עלבון גדול מזה אפילו עושה כן לפי שעה קלה" - "and this is like the analogy of one who seizes the head of a king, pulls it down, and buries his face in a privy full of excrement; there is no greater humiliation than this, even if he does so for only a brief moment."
What should a Jew contemplate in order to grasp just how severe a descent through sin is, even through a light sin? Picture a man coming before the king and saying to him: I would like to bury your head in the privy for just one minute, and then I will immediately take it out. Does it make any difference to the king whether it is done for a second, for an hour, or for a year? As far as the humiliation itself is concerned - the king's humiliation, and the humiliation of a Jew placed in such a state - there is no difference at all. From here one sees the foolishness of distinguishing, in this respect, between a small sin and a great one: in a sin that carries kares the head is buried and the process of extracting it is long, while in a light sin the head is put in and taken out in the blink of an eye, but the situation itself is identical in both.
And this example must not be read as poetic exaggeration: "שהקליפות וס"א נקראים קיא צואה כנודע" - "for the kelipos and the sitra achra are called vomit and excrement, as is known." "Excrement" is the very name by which the kelipos and the sitra achra are called in the accepted terminology, and as is known this is indeed how they are referred to - so the analogy is to be taken quite literally.
Tying the thread together: the flow of the chapters from chapter 17 onward.
Chapter 24 is the summation of a whole series of chapters, all of them aimed at a single idea: how a Jew can arrive, by an easy path - "for the thing is very near to you, in your mouth and in your heart, to do it" - at being careful with every last detail of the Shulchan Aruch.
Chapter 17: the Alter Rebbe concluded the first section of Tanya by establishing that a Jew who sits and contemplates deeply the greatness of the Creator, and thereby awakens within himself the lofty, hidden love, will be able to reach carefulness in keeping Torah and mitzvos. But he himself opened there by noting that serving G-d out of this love runs against one's natural sense and is exceedingly difficult.
Chapter 18: here he opened with an easier path. A Jew's neshamah is like a flame. The flame always strains to reunite with its root, against its own nature and against all logic, and so too the soul always desires to cleave to its root - this is its true will.
Chapter 19: in this chapter the Alter Rebbe explains what confuses the Jew, so that he does not stand in this constantly. It is because it seems to him that even while he sins he remains connected, and he does not realize that something has been extinguished.
Chapters 20-21: as the remedy for removing this illusion, the Alter Rebbe explains at length that the existence of the world is nothing, and the only reality is the reality of the Creator. Anything severed from the Creator, to which one ascribes some significance of its own, is literally avodah zarah - and from here it follows that every sin is avodah zarah and every mitzvah is a connection. This is why "Anochi" is the root of all the positive commandments and "Lo yihyeh lecha" is the root of all the prohibitions.
Chapter 23: the positive side - every mitzvah a person performs is a connection with the Holy One, blessed be He, in that very moment.
Chapter 24: the negative side - every transgression is a severance, and the chapter closes with the analogy of the king's head.
One who sees things this way says to himself, at every light contact with a halachah in Shulchan Aruch: now I have connected myself to the Holy One, blessed be He; and at every transgression: now I have severed myself from Him. Even someone who has no broad knowledge and no deep understanding of lofty matters in G-dliness, matters that would awaken him to love through concepts he cannot relate to - to this, everyone can relate, for there is no person who wants to be severed, and even the lightest of the light does not want it. The whole problem is only that it seems to him that there is a difference between one thing and another.
Therefore let him contemplate the analogy with which the Alter Rebbe sealed chapter 24, the one who buries the king's head in the privy, and let him dwell on it until he keeps constantly before his eyes: the Holy One, blessed be He, says to act this way, and if I act the opposite way, I am severing myself from Him. This contemplation gives him the ability to have it "very near to him" not to stumble in anything at all, and not only in the severe transgressions.
And in the same vein: a person who is prepared to give up his life for kiddush Hashem, why should he shrink from getting up five minutes earlier in the morning, even though in his imagination at that moment it feels harder? The difference comes only from the fact that he is not living what is happening in that very moment. True, mesirus nefesh is a one-time event, whereas this standing firm is demanded anew every single morning - and precisely for that reason the contemplation must be set before one's eyes each and every day.
And this is the precision of the verse: "for the thing is very near to you, in your mouth and in your heart, to do it." If the thing is very near and accompanies a person at all times, like a shadow that goes along with him, then there is never any room for severance - for at any given moment the person stands in that closeness and in its potential. The only thing that can happen is that he forgets that it is near to him, and forgetting is not severance.
In summary: in this section we learned that although the severance is equal in every transgression, the blemish differs from sin to sin, and according to the measure of the blemish the scouring and the punishment are determined - whose entire purpose is cleansing and not vengeance. We saw that the divine soul remains faithful to Him, may He be blessed, even at the moment of the sin, except that it is in a state of actual exile, since its root is from the supernal chochmah, "and He, may He be blessed, and His wisdom are one." We dwelled on the analogy of the king's head buried in the privy, which teaches that as far as the humiliation itself is concerned there is no difference between a brief moment and a long stretch of time. And we tied the thread from chapter 17 onward: the path of contemplating that every mitzvah is a connection and every transgression a severance - a path equally accessible to every soul, in which "for the thing is very near to you" is fulfilled.
In the next section we will turn, with G-d's help, to chapter 25.