Sukkos renews the Ruach after Yom Kippur

איתא במד' ולקחתם ביום הראשון ראשון לחשבון עונות כו'.

It is brought in the Midrash: "And you shall take on the first day" (Vayikra 23:40) — "first for the reckoning of sins," etc.

The Midrash notes that this "first day" of Sukkos is the first day on which the reckoning of sins begins anew.

ומקשין וכי בין יוהכ"פ לסוכות הותרה הרצועה לעשות כל אשר יחפוץ.

And they ask: is it then that between Yom Kippur and Sukkos "the strap is loosened" to do whatever one wishes?

The obvious question: how can the reckoning of sins only begin on Sukkos — does that mean the days between Yom Kippur and Sukkos are free for sin without consequence?

אבל יובן עפ"י מ"ש בזוה"ק נשא ע"פ אשרי אדם לא יחשוב ה' לו עון אימתי כשאין ברוחו רמיה כו' ע"ש.

But it can be understood according to what is written in the Zohar Hakadosh (Naso) on the posuk "Fortunate is the man to whom Hashem does not reckon iniquity" (Tehillim 32:2) — when? When there is no deceit in his spirit (ruach), etc. See there.

The Zohar explains that the "iniquity not reckoned" applies specifically when a person's ruach (spirit) is intact and free of deceit.

דהנה יש נפש רוח נשמה.

For behold, there are Nefesh, Ruach, and Neshamah.

The soul has three levels — Nefesh, Ruach, and Neshamah — corresponding to ascending degrees of spiritual life.

וכפי המעש"ט כן מאירין הנר"נ.

And according to one's good deeds (maasim tovim), so do the Nefesh, Ruach, and Neshamah shine.

These three levels of the soul are illuminated in proportion to a person's good deeds.

ולפי החטא נסתלקין ולכן חטא עון ופשע מכוונים מול אלו הג'.

And according to the sin they withdraw; therefore cheit, avon, and pesha (the three categories of sin) correspond to these three.

Sin causes these three soul-levels to depart; the three classes of transgression — cheit, avon, pesha — damage the Nefesh, Ruach, and Neshamah respectively.

וכשאדם שומר הרוח אז לא יחשב עון.

And when a person guards the Ruach, then "iniquity (avon) is not reckoned."

"Avon" corresponds to the level of Ruach; when one keeps his Ruach intact and free of deceit, that category of sin is not held against him.

וכתיב לב טהור ברא כו' ורוח נכון חדש.

And it is written, "Create for me a pure heart... and renew within me an upright spirit (ruach nachon)" (Tehillim 51:12).

Dovid HaMelech asks for both a pure heart and a renewed, upright Ruach — the two go together in the work of teshuvah.

ולכן אחר יוה"כ שנטהרו לבות בנ"י זוכין בסוכות לרוח נכון וחדש.

Therefore, after Yom Kippur, when the hearts of Bnei Yisrael have been purified, they merit on Sukkos to an upright and renewed Ruach.

Yom Kippur achieves the "pure heart"; Sukkos then completes the process by granting the "renewed, upright Ruach."

וע"י הלולב ומיניו מקבלים הרוח.

And through the lulav and its species, they receive the Ruach.

The mitzvah of the four minim is the vehicle through which Bnei Yisrael receive this renewed Ruach.

ולכן יש ד' מינים כמ"ש מארבע רוחות בואי הרוח.

And therefore there are four species, as it is written, "From the four winds (ruchos) come, O spirit (ruach)" (Yechezkel 37:9).

The four minim correspond to the four directions, drawing in the Ruach "from the four winds" as in Yechezkel's prophecy of revival.

ולכן בין יוהכ"פ לסוכות אין עונות פוגמין הרוח.

And therefore, between Yom Kippur and Sukkos, sins do not damage the Ruach.

During this special interval the Ruach is being renewed, so it is protected and is not blemished by avonos.

הגם כי בודאי נענש אדם על כל חטא ועון.

Even though a person is certainly punished for every cheit and avon.

This does not mean sin carries no consequence — one is still held accountable for every transgression.

רק ראשון לחשבון עונות.

Rather, it is "first for the reckoning of sins."

The Midrash's point is only about when the formal reckoning begins, not that sin is permitted.

הואיל ובראשון הוא הזמן לקבל הרוח הוא ראשון לחשבון עונות כמ"ש:

Since on the first day is the time to receive the Ruach, it is therefore "first for the reckoning of sins," as stated.

Because the renewed Ruach is only received on the first day of Sukkos, that is precisely when the new reckoning of sins — which is measured against the Ruach — can begin.

Summary: The soul has three levels — Nefesh, Ruach, and Neshamah — corresponding to the three categories of sin (cheit, avon, pesha). Yom Kippur purifies the heart, and Sukkos, through the four minim drawn "from the four winds," grants a renewed, upright Ruach. Therefore in the days between Yom Kippur and Sukkos sins do not yet blemish the Ruach, and the first day of Sukkos — when the Ruach is received — becomes the first day of the new reckoning of sins.