Dora Bas Rivka Silver O'H
The angel brought Ezekiel back by way of the eastern gate. This gate had opened to admit G-d's presence (in the previous chapter), but it was now closed. G-d told Ezekiel that the eastern gate was to remain closed, since it was the gate He had used. There was only one exception: the "Nasi" (ruler) was allowed to use that gate. Rashi believes the leader referred to is the Kohein Gadol, since the verse speaks of him eating there and the Kohein Gadol would have eaten sacrificial food. Most commentators, however, including the Radak, say that it is the Moshiach (Messiah), who will rule as king, since the tern "Nasi" is used elsewhere to describe him. Whoever he is, this Nasi is also allowed to come and go by the same gate, which we will see in chapter 46, other people were not permitted to do.
The angel brought Ezekiel by the northern gate, where he saw the glory of G-d had filled the Temple and he fell on his face. G-d told Ezekiel to note well all the details of the Temple so that he will fully understand them. Ezekiel should tell the people that they've done enough with their abominations, allowing those of uncircumcised hearts and uncircumcised flesh to serve in the Temple. ("Uncircumcised heart" refers to apostate Jews, who have rejected G-d in favor of idolatry. "Uncircumcised flesh" refers to kohanim who were not circumcised for medical reasons. This is not a sin, but they are not permitted to serve in the Temple.) By allowing people with these physical or spiritual disqualifications to serve in the Temple, the people failed in their responsibility to safeguard the sanctity of the sacrifices.
The only ones qualified to serve in the Temple are Levites who never served idols. A Levite who once worshipped idols and repented will be forgiven, but will be limited in the role they can play in the Temple service. They can slaughter sacrifices (which need not be done by a Kohein) and can assist the people bringing offerings, but they cannot be involved with the altar or offerings of holiness. They must bear the consequences of their actions, though G-d will make them watchmen in the Temple. The Kohanim, descendants of Tzadok, who remained true while the rest of the nation was straying, will serve in all priestly functions and matters of holiness.
The priests are to wear linen vestments when they serve in the inner court; they are not permitted to wear wool. They must gird themselves in a place that does not sweat, which is why their belts were worn rather high. When they go to the outer court, they are to change clothes and not mingle with others in their priestly garments. They must keep their hair neatly trimmed, neither shaved nor too long. The priests may not drink wine before performing their service in the inner court. They may not marry divorcees or women widowed from Israelites, only Israelite virgins or the widows of other Kohanim.
The Kohanim are to instruct the people in religious matters, teaching them to differentiate between holy and profane and between pure and impure. They shall serve on courts to judge financial disputes and, of course, they are responsible for the sacrifices of Sabbath and holidays. The kohanim may not become impure for a corpse, except to bury a parent, sibling or child. ("Wife" is not listed here, as a kohein is permitted but not required to do so.) The kohanim have received the priesthood as their inheritance, rather than real estate. They get to eat certain sacrifices and gifts as their payment. While they may eat many things that others may not, they may not eat non-kosher animals, so they must be careful in performing sacrifices not to do anything to render them unfit.
You will notice that many of the rules for kohanim outlined in this chapter are more stringent than the way we know them to be (for example, that a kohein may not marry the widow of an Israelite, which according to the Torah he may). In fact, the rules in this chapter more closely approach those of the High Priest. The Radak says that this reflects the greater spirituality in the third Temple.