The establishment of the priesthood represents a profound historical and spiritual act of grace, elevating one family to serve as the exclusive mediators between God and the nation. Aaron was chosen from among all the tribes of Israel, a decision that fundamentally shifted the original spiritual order. Initially, the firstborns of every tribe were meant to perform this sacred service. Furthermore, the original divine plan designated Moses as the priest and Aaron as the Levite. However, because Moses refused his mission at the burning bush, the eternal priesthood was transferred to Aaron [אלשיך]. This elevation places the priest in a unique dual role, serving simultaneously as the representative of the Israelites and as the messenger of God [מלבי״ם].
The responsibilities granted to the priesthood unfold in three ascending stages of holiness. The first duty is the physical act of offering sacrifices upon the altar. The second is the burning of incense. The third and highest duty involves wearing the sacred garments. This final stage symbolizes the role of the High Priest and encompasses the most sacred services, such as those performed on the Day of Atonement [אלשיך].
In return for serving as a mediator, the priest receives an extraordinary reward in the form of portions from the sacrifices and specific priestly gifts [מצודת ציון, ביאור שטיינזלץ]. This arrangement contains a deep spiritual privilege. God essentially transfers to the priests the very portions of meat that were originally designated for the altar fire. When the priests consume these portions, the act of eating is elevated and considered as if the meat had been consumed by the fire of the altar itself [אלשיך, מלבי״ם].
Understanding this divine arrangement highlights the severe misconduct of Eli's sons. God generously granted the priests exclusive rights to His own designated portions of the offerings. However, He never gave them any claim to the portions that belonged to the people bringing the sacrifices. Consequently, when the priests forcefully took meat from the owners' share, their actions constituted outright robbery and corruption [מלבי״ם].