פירוש על עבודה זרה 144:13

The Talmud now tries to prove that it does serve as a connecting link from the first half of the mishnah. How does the wine in the funnel become yayin nesekh—through downward flow, it is suggested. The bottom wine which is yayin nesekh flows up into the funnel and contaminates it.

R. Hiyya says that it is not flow that causes the wine in the funnel to become nesekh. It is the fact that wine in the flask overflows and actually goes up into the funnel. The wine in the funnel is not “connected” to the yayin nesekh below. It is the same wine. As many of you know, I dabble in homebrewing. Whenever I fill up a bottle, I use a filling tube. The beer from the bottom always flows up onto the part of the tube that’s in the bottle. If you want to fill up a bottom container with a funnel, this is what will happen.

The Talmud points out here that while we cannot use the mishnah to prove that flow is a connecting link, the opposite is also not true—we cannot use the mishnah to prove that it is not a connecting link. All that we can learn is that when the lower wine reaches back into the funnel, the wine in the funnel is prohibited.

A Jew pours wine from his vessel directly into that of a non-Jew. The wine in the upper vessel remains permitted. The Talmud (somewhat strangely) deduces from here that the wine in between the two vessels is forbidden, and thus tries to prove that flow is considered a connecting link.

If flow contaminates the upper liquid, then the wine in the container should also be nesekh. The Talmud has to therefore say that the baraita refers to a case where he cuts off the flow from the top to the bottom before it reaches the bottom container. This would seem to be a recipe for mess.

The second clause in the mishnah says that the wine in the bottom vessel is prohibited. We could deduce that what is in between is permitted, leading to the conclusion that flow is not a connecting link.
In the end, nothing can be learned from this mishnah concerning the concept of flow. [I might add that clearly the simple reading of the mishnah is that downward flow is not a connecting link. The Talmud does not seem to want to prove this quite yet].

This baraita seems to imply that flow is a connective. As soon as the wine flows out of the cask into the vat of yayin nesekh, the wine becomes prohibited. R. Sheshet says that the baraita refers to a case where a non-Jew is doing the pouring. Thus he invents a new category that is not found in tannaitic sources—wine poured by a non-Jew is considered nesekh.

The Talmud here refines the prohibition of wine poured by non-Jews, which was created above by R. Sheshet. This is considered to be a rabbinic decree, an add-on if you will to the main prohibition of yayin nesekh. Since it is an add-on, the rabbis can shape it the way they want. So the rule is that if the gentile pours the wine, what comes out is prohibited but what is inside is permitted. This, by the way, is why in kosher restaurants non-Jews do not pour wine for the customers. What comes out of the bottle is prohibited, even though the non-Jew never touched it.

R. Hisda does not want the Jewish wine dealers to pour directly into non-Jewish containers. Evidently he thinks that flow does cause a connecting link and the fact that the bottom wine is nesekh will contaminate the wine in the Jewish container.

Rava thinks that wine poured by a non-Jew is prohibited, even if he is only assisting a Jew. Therefore, when pouring wine, Jews should make sure that non-Jews do not help pour out the wine in any way.

The non-Jew puts his hand at the end of the siphon, and therefore, the entire barrel of wine is resting on his hand—if he took his hand away, the wine would flow out through the siphon. Therefore, Rava prohibits the entire barrel.

The instrument referred to here is a multiple straw which allows many people to drink at the same time. As long as the Jew is drinking, he will not be drinking the backwash of the nonJew. But if the non-Jew stops while the Jew is still drinking, some backwash may go in, and the Jew might drink wine that is considered nesekh. I’m putting a picture in here of people in modern Uganda drinking beer through a straw. This instrument is very common in the ancient and modern world for beer drinking. It would allow many people to share the beer and for the beer to be filtered. Traditional beer would have been full of a large amount of sediment.

Such a device was evidently used at the house of the exilarch, the Jewish governor in Babylonia. It is not surprising to hear that in such a place, Jews and Gentiles would drink together. In any case, the rabbis permitted, and maybe even used, this device.