Commentary for Avodah Zarah 112:10

There are two resolutions to this difficulty. First of all, it may be that the entire comparison between tithes and yayin nesekh is unjustified. The rabbis were strict when it came to yayin nesekh—the liquid is subject to becoming yayin nesekh as soon as it goes down into the vat, even before it is skimmed. The dispute was only with regard to tithes.
But Rava did use a baraita about tithes in his understanding of the mishnah. Therefore, he must posit that there are indeed three opinions.

A wicker basket separates the liquid in the upper press from that in the lower vat. The basket serves to strain out the skins and seeds. According to R. Huna, when the mishnah taught that the liquid in the upper press is permitted it is referring to a case where he did not put back that wicker basket. But if he did put the wicker basket back in, all of the wine, even that in the press, becomes prohibited. This is because the wicker basket contains some prohibited wine which then mixes in with the permitted wine in the press, causing it all to become prohibited.

The question is asked how the contents of the wicker basket became prohibited. The answer is through a concept called “nitzok” which I have translated as a “poured stream.” This means that when there is an upper vessel flowing into a lower vessel, although in reality liquid only flows downward, we consider the contents of the upper vessel to have the same status as the contents of the lower one. The contents of the lower vat flow upward to the wicker basket and make this liquid prohibited as well. Then this liquid contaminates that in the wine press, if he puts the basket back.
Note that the contents are not considered as contaminating the liquid in the wine press. The commentators explain that this is because this is two stages removed, and while some might say that the status goes up one stage, to the wicker basket, all agree that it does not go up to the press.
The Talmud notes that if we read R. Huna this way, then we have decided that “a poured stream serves as a connective.” This is a debated issue that appears later on in the next chapter and the Talmud does not think that R. Huna necessarily holds that it is.

The Talmud rejects the implication R. Huna rules that poured streams always serve as a connective. Rather, this may be a case where the wine in the vat actually overflowed and physically went up into the wicker basket. This is not an issue of “nitzok.” Rather, the wicker basket has wine from the vat in it and this wine then mixes back with the liquid in the press and causes it to become prohibited.

Fascinatingly, we hear of a six year old boy who had learned, meaning memorized, tractate Avodah Zarah, probably of the Mishnah. With this knowledge in hand, he is asked a question of law—can a Jew tread on grapes with an idolater? And the answer is clearly in our Mishnah—yes he can.

The person who asks the boy this question asks two follow-up questions. First of all, when the idolater touches the liquid, does he not render it yayin nesekh? This very question shows a shift from the mishnaic law to the amoraic law. According to the mishnah, the liquid in the press is not considered “wine” and is therefore not subject to the laws of libated wine. Idolaters libate wine, not unfermented grape juice. There is thus no problem with their having contact with the latter.
In contrast, according to the amoraim (or at least some of them) all liquid is subject to these laws. Therefore, according to the boy, we must make sure he does not libate any wine by tying up his hands. This is, of course, an absurd resolution and effectively makes it impossible to the Jew to tread with the idolater.
But the idolater’s feet will still touch the wine, protests the questioner. Again, we can see here that the understanding of the status of the liquid in the press has changed. Furthermore, it seems that the questioner understands the non-Jews to be defiling the wine in a way similar to the rules of impurity, and not the rules of yayin nesekh. Defiling is done through contact and it does not matter whether this contact is by hand or foot. The boy rejects this concept and answers that wine touched by feet does not count as yayin nesekh.
It is interesting that the Talmud attributes this discourse to a six year old boy. I’m not familiar with other such cases in the Talmud (there may be some, but I just do not know of them). Perhaps the idea is that Avodah Zarah is such an important tractate, that even six year olds should know it. In a world saturated with idolatry, where assimilation was such a huge threat (perhaps even more than in our day), this tractate was especially important.

Again, according to the mishnah it would seem that Jews and idolaters can press wine together. And thus, in the Babylonian town of Nehardea they do so. But the question is put to Shmuel whether this wine it is permitted to sell or drink this wine and he delayed three festivals before answering.

The Talmud now tries to figure out why Shmuel had to delay three festivals before answering. The first reference point is a baraita in which R. Natan and the other sages (later assumed to be R. Shimon) argue about a case where an idolater measured the amount of wine in a vat with his arm or leg. Clearly in such a case the idolater did not intend to libate the wine. Nevertheless, R. Natan says that if he touched it with his hand, it is prohibited to derive any benefit from the wine. The sages say it may be sold, but they agree that it may not be drunk.
The problem is that even if Shmuel holds like R. Natan, it is prohibited only if he touched it with his hand. The people pressing the grapes touched it with their feet only. So even if he held like R. Natan, he should have allowed them to sell it.