When a pure object and an impure object are inside the same vessel, under certain circumstances, the impurity can pass from one to the other. On today’s daf, Rava teaches:
In a case where one divided a tenth of an ephah of a meal offering into two halves, and one half was lost and he separated another half in its stead, and afterward the first lost half was found, and all three are placed in a receptacle together, if the one that had been lost became impure, the previously lost half and the first half join together and become impure, but the half that was separated to replace the lost half does not join together with the other halves, and it remains pure.
The standard size of a meal offering is a tenth of an ephah. In this case, the offering has been separated into two equal parts, each a twentieth of an ephah. Let’s imagine these as two oily dough balls. One of these balls (A) is lost, leaving the other (B) as an incomplete offering. To proceed, a new ball of dough (C) is brought forward to be combined with B. But before the offering is completed, A is found and placed in the vessel that holds B and C, but does not make physical contact with them. Then, A becomes impure. Does it “infect” the other two?
Rava teaches that A’s impurity is passed on to B, as they were once two halves of the same offering. C, however, which was never paired with A, is still considered separate and remains pure.
Similarly, Rava continues, if it is C that initially becomes impure, B contracts the impurity, because B and C were paired together during the time when A went missing. A, having never been paired with C, remains pure.
Finally, Rava teaches that if it is B that became impure, both A and C do so as well, as each of them was paired with B at some point (A originally, and C when A was lost).
Had Rava been striving for brevity he might have taught the following: When half a meal offering becomes impure, it passes on the impurity to all half portions that were at one time paired with it and that are, at that moment, residing in the same vessel.
Abaye disagrees with his colleague, and presents a different opinion:
Even if any one of the half-tenths became impure, both remaining half-tenths join together and become impure as well. What is the reason? They are all residents of one cabin.
In other words, according to Abaye, all three of the portions were designated to be part of the same sacrifice and, as a result, they are still connected to each other. By virtue of this connection, should any one of them acquire ritual impurity, it is passed on to the others. This is where they differ: Whereas Rava held that A and C do not transmit impurity one to the other, Abaye holds that they can.
If the law was determined by ease of understanding (or brevity of presentation), Abaye would carry the day. Yet that is not how the Talmud makes decisions. In the copious talmudic debates between Rava and Abaye, the law follows Rava in all but six cases. This is not one of those six.
However, the practical application of this rule is not what’s most important here, especially because the likelihood of this actually happening is slim — even if Temple rituals were still being practiced. At the heart of this dispute is the connection between two half portions of a meal offering and whether or not it is strong enough to allow impurity to pass from one to the other when there is no physical contact between them. Should we consider them to be part of a whole because they are both affiliated with the same particular sacrifice? Or, must they have been actually designated, at some point, as a whole offering? This ultimately sheds light on two legal perspectives on how we might think about the matter. And that, one could argue, is one of the things that the Talmud does best.
Read all of Menachot 24 on Sefaria.
This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on February 4, 2026. If you are interested in receiving the newsletter, sign up here.
