Avodah Zarah 73

The mishnah on today’s daf explains what happens if yayin nesekh, wine dedicated to idolatry, is mixed with kosher wine. 

Wine used for a libation is forbidden, and any amount of it renders (other wine) forbidden.

Even a drop of yayin nesekh contaminates kosher wine. The mishnah then articulates a more general principle: 

A substance with the same substance (renders the mixture forbidden) with any amount, but with a different substance — when it imparts flavor.

Any amount of yayin nesekh that mixes with other wine renders the wine forbidden. But if the yayin nesekh is mixed with water, it only makes the water forbidden if the water starts to taste like wine. Simple enough. But today’s daf immediately brings a teaching that contradicts this principle: 

When Rav Dimi came, he said that Rabbi Yohanan says: One who pours wine used for a libation from a barrel into a cistern, even all day long, it is nullified little by little. 

Rabbi Yohanan seems to think that idolatrous wine can be cancelled out by enormous quantities of kosher wine. In this case, each drop of wine is immediately nullified by the greater quantity of wine in the cistern and, once nullified, the drop becomes part of the total volume of kosher wine. So even if you pour barrels of yayin nesekh into a cistern all day, such that by the end of the day the majority of the wine in the cistern clearly originated from the barrels of yayin nesekh, all the wine is all permitted for Jewish consumption. 

How to resolve what seems to be a clear contradiction between Rabbi Yohanan and the mishnah? The Talmud offers a neat resolution.

What, is it not where the forbidden substance fell into the permitted substance? No, where the permitted substance fell into the forbidden substance.

The Talmud reads the mishnah as forbidding mixed wine when the kosher wine fell into a vat of yayin nesekh (and so gradually took on its forbidden status). By contrast, Rabbi Yohanan rules in a case where the yayin nesekh fell into a vat of kosher wine. By suggesting that their rulings are responses to two very different cases, the Talmud insists that Rabbi Yohanan and the mishnah don’t actually contradict each other, and in fact agree on the principle of gradual nullification in a larger volume of liquid.

It feels odd to insist that non-kosher wine can be nullified so easily (well, as long as you have large cisterns of kosher wine available). If a status can be easily nullified, is it even meaningful in the long term?  The Talmud cites another version of Rabbi Yohanan’s tradition which makes it a little harder to nullify idolatrous wine: 

When Rav Yitzhak bar Yosef came, he said that Rabbi Yohanan says: One who pours wine used for a libation from a small canteen into a cistern, even all day long, it is nullified little by little. And this applies specifically to a small canteen, whose stream is not significant. But from a barrel, whose stream is significant, no.

According to this version of the teaching, yayin nesekh is only nullified when small amounts are poured in at a time, no more than what can be poured from a small canteen. You can’t just tip over a giant barrel of non-kosher wine and nullify the whole thing. You have to do it small canteen by small canteen, which will take some time. And indeed, the Shulchan Aruch follows this version of Rabbi Yohanan’s teaching, permitting the nullification of yayin nesekh in a cistern only if poured from a small canteen.

Today’s daf highlights a tension that we’ve seen throughout the tractate: a desire to create and enforce boundaries between Jews and non-Jews, and legal strategies that erase or at least blur those boundaries. And while this particular discussion leans in the direction of blurring boundaries, it insists that you have to put in the work to blur those boundaries effectively. 

Read all of Avodah Zarah 73 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on August 30, 2025. If you are interested in receiving the newsletter, sign up here.