The obligation to repent (teshuvah) is a central theme in Judaism that applies throughout the year and throughout one's lifetime. Chazal register the effectiveness of teshuvah even at the end of a lifetime of sin - "afilu rasha kol yamav ve-asah teshuvah ba-acharonah ein mazkirin lo avonotav".
However, teshuvah attains special prominence in the period defined as "asseret yemei teshuvah", inaugurated by Rosh Hashanah and culminating with Yom Kippur (Rosh Hashanah 18b). The special requirement of teshuvah during these days cannot be attributed only to the urgent need to achieve a positive judgment for the upcoming year. Nor does the fact that this period, punctuated by the spiritually inspiring experiences of Rosh Hashanah and Yom Kippur, is particularly conducive to accomplishing teshuvah sufficiently explain the phenomenon.
The singular status and character of teshuvah in this period is reflected in numerous sources. The Sefer ha-Chinukh (no. 364) concludes his general discussion of the mitzvah of teshuvah by asserting that one who neglects to engage in this ubiquitous obligation of repentance specifically on Yom Kippur is guilty of actively rejecting this imperative. The Rambam (Hilchos Teshuvah 2: 7) formulates the broader mitzvah of teshuvah as the obligation to accompany one's repentance with viduy - confession. Only in connection with Yom Kippur does he actually record an obligation to repent! R. Yonah, in his classic exposition on teshuvah, Shaarei Teshuvah (2:4,17), lists teshuvah on Yom Kippur as an obligation independent of the universal mitzvah of teshuvah, based on the verse "lifnei Hashem titeharu" (Vayikra 16:30), which he interprets not as a promise but as an imperative. What is the special character of repentance on Yom Kippur reflected by these unusual treatments?
The constant obligation to do teshuvah is generated by the act of sin which distances the transgressor from Hashem and triggers punishment. In order to redress this specific violation and absolve oneself, one must engage in the process of repentance and confession. The Rambam begins Hilchot Teshuvah with a description of these factors and this process. The focus of such repentance is the neutralization of each specific sin and the restoration of the relationship with Hashem that prevailed prior to the individual infraction.
However, precisely because the period of asseret yemei teshuvah is triggered by the calendar, by the need to face judgment and by the opportunity to begin a new year with an intensified religious commitment, the focus and orientation of the teshuvah is different. The fact that one needs to address all previous transgressions at once contributes to the singular nature and ambition of Yom Kippur's teshuvah process. In the effort to contend and confront all sins one necessarily engages in a holistic reassessment that includes but transcends individual halachic violations. Moreover, the teshuvah of this period is linked to the central motif of total devotion to Hashem (kulo la-Hashem) that is accentuated on Yom Kippur, a day of pure spirituality in which human beings vie with the angels on high in expressing their absolute and single-minded religious commitment.
The long confession of Yom Kippur (al cheit) begins with accidental transgressions (ones) that do not actually engender punishment and that possibly don't even require repentance according to the rules hat govern the rules of teshuvah all year long. The fact that intentional and accidental infractions (ones ve-ratzon) are grouped together at the outset of the process despite evident crucial differences, reflects the wide range and transcendent ambition of a more holistic repentance. The list includes broader categories of sin, as well as the mere intention to sin, alongside specific violations. It is noteworthy that the entire confession litany is recited irrespective of specific guilt. Significantly, the halachah asserts that one continue on Yom Kippur to confess transgressions that were neutralized in years past. Moreover, we seek on this day not merely to restore our relationship with Hashem but to intensify and enhance it. The sense of alienation experienced due to sin becomes a catalyst for the refashioning of one's religious persona.
The confession list introduces olah (burnt offering sacrifices) violations before chatat (sin offerings) transgressions. This seems perplexing since the offering of korban chatat always precedes korban olah [Zevachim 7b. See parallel discussion of Magen Avraham OH 1:5.] However, it is the olah that uniquely captures the opportunity, ambition, and focus of Yom Kippur. While the chatat focuses on neutralizing each individual sin, and that, too, is a priority on Yom Kippur, it is the olah that conveys the total commitment of "kulo la-Hashem", symbolized by the fact that it is totally consumed on the mizbeach. Moreover, the olah addresses the totality of the religious personality and experience, confronting also the neglect of spiritual opportunity (mitzvot aseh) and improper attitudes and intentions (hirhurei aveirah). The teshuvah of Yom Kippur, then, accentuates olah even as it includes chata.
This ambitious, transcendent and holistic approach to teshuvah is conveyed by the independent source for repentance on Yom Kippur that is cited by R. Yonah'- "lifnei Hashem titeharu". Taharah (ritual purity) demands a holistic and comprehensive approach; it cannot be achieved piece-meal. Only one who immerses himself fully in the mikveh addressing all of his impurities simultaneously can attain the objective. Sefer ha-Hinuch projects the idea that while ignoring individual violations year-round is an act of neglect and the squandering of an opportunity, the failure to confront the challenge of teshuvah on Yom Kippur in the context of the stakes and opportunities for a comprehensive realignment of ones relationship with the Hashem constitutes an emphatic rejection of the very concept of teshuvah. The Rambam formulates repentance as an obligation only on Yom Kippur precisely because the artificial time-frame underscores and facilitates teshuvah's transcendent orientation.
Despite their assertion of the unique character of the teshuvah of Yom Kippur, it is noteworthy that, unlike R. Yonah, the Rambam and Sefer ha-Hinuch integrated their treatment of teshuvah on Yom Kippur with their discussion of year-round and life-long teshuvah. In fact, the Rambam omits any reference to teshuvah in Hilchot Shevitat Asor, the section dedicated to the laws of Yom Kippur. This reflects a profound truth that is echoed by the Maharsha (Megilah 32a). He notes that Moshe's enactment that one begin to review the halachot of a particular festival in the preceding month was never articulated with respect to Rosh Hashanah and Yom Kippur. The Maharsha explains that the theme of teshuvah that dominates this period belongs to the entire year, while Moshe's takanah applies only to themes that are unique to a particular festival. The concept of teshuvah, as manifest on Yom Kippur is a paradigm that is meant to inspire us to achieve great spiritual heights and to develop a comprehensive halachic personality all year round. Because of its singular character, Yom Kippur is both the most unique and most relevant day of the year!