Introduction to Nidah

1) Shamai holds 'Kol ha'Nashim, Dayan Sha'atan'.

(a) What does this mean?

(b) What do Hillel and the Chachamim hold?

(c) Why should a woman become Temei'ah retroactively, anyway?

(a) What is a woman who has a Veses, and how does her Din differ from that of a woman who does not?

(b) What are 'Eidim' (in the context of Tum'as Nidah), and what is the Din of a woman who uses 'Eidim' when she is with her husband?

(c) From when does she begin counting her days of Nidus?

What is Hillel's counter-argument?

4) By Dam Nidus, the blood is now there, and it could possibly have dripped slowly, in a way that was not noticeable - just like by a Mikveh. In that case, the Din in our Mishnah differs from the Din by a Mikveh that was found to be short of forty Sa'ah, and which is Tamei retroactively (not like Shamai) and not be'Safek, but definitely Tamei (not like Hillel, who holds that, by Nidah, she is only Safek Temei'ah)?

(a) What is the difference whether it is Safek Tamei or Vaday Tamei?

(b) How do we know that in the case of Mikveh, the Tumah is Vaday and not Safek?

(c) How do both Shamai and Hillel resolve this discrepancy?

(a) What is the Din (either according to Rebbi Yochanan or according to Rebbi Yehoshua ben Levi) if someone discovers that the barrel containing the wine which he was using as Ma'asros on all his other wine, has turned sour (according to Rebbi, who holds that wine and wine-vinegar are two different species)?

(b) Why will this appear to be another discrepancy according to Shamai?

(c) How does Shamai resolve this problem?

(d) How does the Gemara reconcile this Mishnah, which counts the wine as a Safek vinegar, with the Mishnah of Mikveh, which it considers Vaday Tamei - despite the fact that both cases have two shortcomings.