NOTES for Num 8:1-25
The dedication of the Levites to service consists of two elements: a purifying rite connected with washings, and the dedication itself, accompanied by sacrifices. One of them is purifying, completing the process of purification, while the second is already the dedication to service itself. This sequence is entirely understandable if we remember the main meaning of the priestly community's existence as such. That meaning is that among God's people at every moment there must be a certain number of people who are permanently sanctified and therefore permanently remain at the altar, in God's presence, where alone sanctification is possible.
That is precisely why priests were forbidden to leave the court of the Tabernacle, and later the Temple, during the entire time of their service, and why they were prescribed stricter rules of ritual purity. The court of the Tabernacle, like the Temple court, was sacred space. There God's presence was revealed to a person, and the person naturally had to be purified before entering that space, especially for a long time. It would seem: why are additional purifications needed when the Torah already describes in sufficient detail all the cases when purification is necessary?
For us, living in the era of the approaching Kingdom, when death is already far from all-powerful, it is hard to imagine the situation of the pre-Christian world. In those days evil and death reigned over the world absolutely. Death was the last reality, and defilement in all its forms was a manifestation of their power. Death and evil were overcome only by God and only where He was present. Before the coming of Christ, He Himself chose the places of His presence and Himself marked them with the radiance that many saw over the Tabernacle and in the Holy of Holies of the Temple.
When a person found himself in the court of the Tabernacle or the Temple, he passed for a time from the kingdom of death into the kingdom of life, and then returned back again. There, at the altar, was then the only place on earth where death retreated before life. It is no surprise that living there, in this kingdom of life, was a task at least far from simple for a person accustomed to the kingdom of death. That is why, understanding the whole difficulty of the task, the ministers of the altar strove for special purity, so as not to defile the life with which they came into contact.