שמות, פרק כ״ט, פסוק ל׳

Passing the mantle of spiritual leadership is a profound and complex process. When a new High Priest is appointed, he must undergo a full week of initiation and preparation. This transition is not merely an official appointment but a physical and spiritual immersion into the responsibilities of his predecessor. The initiation requires seven consecutive days, without any interruption [רש״י, הכתב והקבלה, גור אריה]. Throughout this entire period, the new leader wears the sacred garments day and night [אבן עזרא]. By remaining continuously clothed in these vestments for a full week, the incoming High Priest is able to deeply internalize the profound meaning and ideals embedded in his new role [רש״ר הירש]. Ideally, this process is accompanied by the anointing of special oil. However, even in times when the anointing oil is unavailable—such as during the era of the Second Temple—the act of wearing the garments for seven consecutive days is sufficient to fully qualify the new High Priest for his duties [תורה תמימה, רש״ר הירש].

The succession of the High Priesthood is firmly rooted in the principle of inheritance. If a High Priest passes away and leaves behind a son who is capable and worthy of the position, that son takes precedence over anyone else and possesses the primary right to inherit the role [רש״י, רלב״ג]. When he rises to take his father's place [רש״י, מזרחי, שד״ל], the title of priest is not treated merely as an honorary designation of authority. Rather, it functions as an active term denoting actual service and labor; the successor is quite literally the one who does the work in his father's place [רש״י, גור אריה, לבוש האורה].

The defining characteristic of the High Priest is his exclusive readiness to enter the innermost sanctum, the Holy of Holies, on the Day of Atonement. While all regular priests enter the Tabernacle for daily duties, only the High Priest achieves the level of sanctity required to step into this most sacred space [רש״י, מזרחי, גור אריה, רש״ר הירש]. Commentators differ regarding what the new High Priest actually does during his week of initiation. One approach suggests that he performs specific tasks while wearing the garments in order to train himself. Another perspective maintains that he is entirely forbidden from performing actual service during these seven days; instead, he simply wears the garments and bows in reverence, only beginning his official duties in the sanctuary after the preparation period has concluded [העמק דבר].

This specific definition of the High Priest's duties also serves to distinguish his role from that of the priest appointed to accompany the army in battle. Unlike the High Priesthood, the position of this military priest does not automatically pass to his son. Leading troops in war requires highly specific psychological traits and a unique talent for reading the environment and encouraging the soldiers to prevent weakness on the battlefield. Because these specific emotional and leadership qualities are not inherently passed down through genetics, relying on automatic inheritance for this role could put the entire public in danger. Therefore, the military priest must be individually selected based on merit and capability every single time [תורה תמימה].