פירוש על קידושין 138:21

Deuteronomy 17:8 uses the phrase “go up” to describe going to the Temple. This demonstrates that the Temple is the highest point in Eretz Yisrael.
Jeremiah uses the phrase brought up to describe people coming to Eretz Yisrael from other countries. From here we can see that Eretz Yisrael is higher than other countries.

The mishnah uses the word Babylon to allude to what Ezra, the leader of the Jewish people in exile, did before he moved to Israel. He made the Jewish community like “sifted flour.” This is taken to mean that he sifted out the best lineages in Israel and left them to run the Babylonian Jewish community. The poorer lineages moved with him to Eretz Yisrael. According to Rashi, he had to do this because he was not leaving behind any sages in Babylonia who could help in the future determine people’s lineage.
While there may be some historical truth in this, at least insofar as the leaders of the Jewish community in Babylonia probably stayed behind, the idea that Babylonian lineage is better than that in Eretz Yisrael is a Babylonian claim that would bolster their leadership during a time of competition with the center in Eretz Yisrael. We shall see this theme quite frequently in this chapter. It is also one I dealt with in my newest book, Reconstructing the Talmud, volume 2.

Abaye and Rava argue over whether the return to Eretz Yisrael after the exile was voluntary. They also seem to argue over how exactly the mishnah is worded.
Abaye holds that the immigration was voluntary and thus he agrees with R. Elazar’s statement about Ezra making Babylonia like sifted flour.
Rava holds that they were forced to go, and since they were forced, everyone knew who was of what lineage without him having to sort it out for them.

Alternatively, both Abaye and Rava could agree that Ezra made Babylonia into sifted flour. Abaye holds that he separated them into lineages and then they voluntarily went to Israel, knowing who could marry whom. Rava says that even though they knew each other’s lineage, he still had to force them to go.

Rav Yehudah said that the lineage of most countries is dough in comparison with Israel, meaning it is all muddled. But Israel’s lineage is more muddled than Babylonia. This works well with Abaye who said that they went up to Israel voluntarily and that Ezra did not sort their lineages out before they went up. There was no oversight as to who could marry whom. But to Rava who said that Ezra forced them to go, Ezra sorted their lineage out. So why is Israel like dough in comparison to Babylonia?
The answer is that while that generation knew its lineage, subsequent ones did not.

According to Abaye, after leaving for Eretz Yisrael, Moshe still had to clarify people’s lineages, as we see in the verse. But according to Rava, he should have sorted them all out from the beginning.
The answer is that Ezra was careful to sort out those unfit to marry into Israel. He knew who the mamzerim and netinim were. But he did not know who were priests, Levites and Israelites. He was less cautious with these groups because they can all marry each other. Therefore, he had to figure this out at a later stage.

According to Abaye, after leaving for Eretz Yisrael, Moshe still had to clarify people’s lineages, as we see in the verse. But according to Rava, he should have sorted them all out from the beginning.
The answer is that Ezra was careful to sort out those unfit to marry into Israel. He knew who the mamzerim and netinim were. But he did not know who were priests, Levites and Israelites. He was less cautious with these groups because they can all marry each other. Therefore, he had to figure this out at a later stage.

The Talmud now cites support for the fact that priests, Levites and Israelites came back to Eretz Yisrael.

The verse and accompanying baraita quoted here proves that halalim, disqualified priests (“they were deemed polluted”), came with Ezra. The Tirshata, understood to be Nehemiah, allowed these disqualified priests to continue to eat the same food they ate while in the Diaspora. This is “sacred food eaten outside of Jerusalem,” namely terumah but not sacrifices. This proves that one is not removed from one’s presumed status without proof. Thus “presumptive status (hazakah)” is great.

The verse and accompanying baraita quoted here proves that halalim, disqualified priests (“they were deemed polluted”), came with Ezra. The Tirshata, understood to be Nehemiah, allowed these disqualified priests to continue to eat the same food they ate while in the Diaspora. This is “sacred food eaten outside of Jerusalem,” namely terumah but not sacrifices. This proves that one is not removed from one’s presumed status without proof. Thus “presumptive status (hazakah)” is great.

The priests referred to in Ezra were allowed to eat terumah. But this could cause a problem if their eating terumah was evidence that they are proper priests and therefore can marry into priestly lineage and their children would be priests. So how could Ezra allow them to eat terumah?
The answer is that in this case, since their presumptive status was weakened and they could not eat sacrifices, everyone would know that the lineage of these priests is flawed. Thus they could eat terumah and their problematic lineage still be known.
[As an aside, this and many other passages, assumed that priests would marry daughters of other priests. The “lineage” referred to here would fit into that situation. However, according to halakhah, priests, Levites and Israelites can intermarry.]

If the priests cannot ascend to the lineage of fully valid priests, then how does this source show us that “presumptive status is great”? On the contrary, it would seem that presumptive status is not so great.
The answer is that in Babylonia they ate terumah whose status is derabanan. Now back in Israel, they are eating terumah whose status is biblical. This is to show you how strong presumptive status is.

Alternatively, we could correct the rule about promoting from terumah to lineage. These priests were eating only rabbinic terumah, even in the land of Israel [this would be terumah from produce not biblically liable for terumah]. And we do not promote from this type of terumah to lineage.

According to this second reading of what these priests did, the greatness of presumptive status is expressed in the fact that now back in Eretz Yisrael, where biblical terumah does exist, the rabbis still let them eat rabbinic terumah. They were not strict lest by eating rabbinic terumah they come to eat biblical terumah. In contrast, in Babylonia, there was no biblical terumah, so there would have been no reason to be strict.

The verse says that these priests could not eat “most holy things”—sacrifices. By implication, they could eat terumah, even biblical terumah.

The Talmud now offers a new explanation of the Tarshita’s words. He did not prohibit only sacrifices. He prohibited anything that is called “holy.” And in Leviticus 22:10 terumah is called holy. Thus, these priests could not eat biblical terumah, but they could eat rabbinic terumah.