At the end of the first ammud we ask a question about why it should have said tzeis havocvim. How does the answer that I would have thought he waits till after the karbon ka Mish milon answer the question. The Mishnah could still have taught tzeis hacochavim and I would learn this. Unless I would think tzeis hacivvaum.of the night after the karbon.
Edwin Chomer, Manchester
1) The answer to the Gemara's question, "Lisni mi'She'as Tzeis ha'Kochavim," is not that we would have thought that he waits until after the Korban. The answer is "Milsa Agav Orchei Ka Mashma Lan Kohanim Eimas Achli bi'Terumah mi'She'as Tzeis ha'Kochavim"; the Mishnah is telling us an incidental Chidush that Kohanim may eat Terumah once the stars come out.
This is because it is obvious to us that one says Shema when the stars come out. The Mishnah does not need to tell us that. Instead the Mishnah tells us something that otherwise we would not have known -- namely that one says Shema at the time that Kohanim can eat Terumah, and now we automatically know that Kohanim may eat Terumah when the stars come out.
Then the Gemara gives us a second "Ka Mashma Lan" (I think that this may be a source of confusion, that there are two "Ka Mashma Lan"s in the Gemara). The second Ka Mashma Lan is that "Kaparah Lo Me'akvah"; once the stars have come out the Kohanim may eat Terumah even before they have brought their Korban.
If the Mishnah would have taught "Tzeis ha'Kochavim," we would have known that one says Shema when the stars come out but we would be missing two items of knowledge about Kohanim: (a) they may eat Terumah once the stars come out, (b) they may eat Terumah even before they bring their Korban.
I do not see how we might have thought that Tzeis ha'Kochavim is the night after the Korban. The Korban is brought in the daytime and as soon as it is brought they may eat Terumah.
2) I saw that both the Hebrew Mesivta edition and the Hebrew Artscroll edition understand that there is only one Chidush of the Mishnah -- namely that Terumah may be eaten before the Korban is brought, while the fact that they have to wait until Tzeis ha'Kochavim in order to eat Terumah is not considered a Chidush. So even though the Gemara says Ka Mashma Lan twice, there is actually only one Chidush in the Mishnah. I spoke to a Talmid Chacham and he also learned this way.
This is not as I wrote above, and according to their way of learning you are correct, Edwin, that the answer of the Gemara to the question, "Why does the Mishnah say Tzeis ha'Lochavim?" is indeed, "I would have thought that he waits until after the Korban."
However, I remain with my view and argue that there are two Chidushim in the Mishnah. I cite support for my argument from ha'Me'or ha'Katan (printed next to the Rif in the back of the Gemara) who writes that there is a Havah Amina in the Gemara that Kohanim may eat Terumah once the sun sets and do not need to wait for the stars. So I argue that the first Ka Mashma Lan of the Gemara is that the Mishnah is telling us that sunset is not sufficient and they have to wait for the stars.
At any rate, I stay with my answer to your question, that the Mishnah could not have taught Tzeis ha'Kochavim because if it would have done that it would not have mentioned Terumah and we would not have known the Halachos about Terumah.
Kol Tuv,
Dovid Bloom