Question: The Yerushalmi queries this from the fact that Yerushalayim is a town where the Minhag is not to do work (on Erev Pesach) ...

Question (cont.): What the Yerushalmi means is that one can assume this to be the case, seeing as gathered there from all over, even from places where it was customary to be strict in this regard.

Answer: And the Yerushalmi answers that they looked as if they were plowing, although in reality, they were not.

Explanation #1: Rashi explains that he(Abaye) learn it from the Pasuk in Chagai "el ha'Lechem ve'el ha'Nazid".

Explanation #2: According to Rabeinu Tam however, who explains later (Daf 17.) "or to the pottage" (rather than 'and') ...

Explanation #2 (cont.): The Ri explains that he learns it from (the Pasuk) "And the meat that touches anything that is Tamei shall not be eaten" - even (if it touched) food.

Explanation #2 (conclusion): And we learn T'rumah (And not just Kodshim -See Tosfos Rabeinu Peretz) from the fact that since the Pasuk that teaches us that food cannot be Metamei food can no longer be referring to all cases (seeing as by Kodshim it does), we establish it by the single most likely case - Chulin! (See Hagahos ve'Tziyunim).

Halachah (Proof #1): The Riva extrapolates from here that even less than a Revi'is of liquid is subject to Tum'ah.

Halachah (Proof #2): And later on too (on Daf 17:) the Gemara says with regard to water that 'Less than a Revi'is becomes Tamei'.

Implied Question: And when the Gemara states in Perek Ein Ma'amidin (Avodah_Zarah 19: & 20.) that 'a Revi'is of Yayin Nesech is subject to Tum'ah, and likewise in the second Perek of Nidah (Daf 19:) with regard to greenish blood, and in many other places?

Answer #1: The Riva establishes that Sugya by (the Tum'ah of) P'sul Geviyah, whose Shi'ur is a Revi'is, as we learned in Me'ilah, in Perek Kodshei Mizbe'ach Daf 17:) that 'All beverages combine to make-up the Shi'ur Revi'is, to renders Pasul the one who drinks them.

Answer #2: The Ri however, explains that when a Revi'is is required, it is for liquids whose Tum'ah is not min ha'Torah, such as S'tam wine of Nochrim and greenish blood, which are not subject to Tum'ah min ha'Torah, even if they comprise more than a Revi'is; whereas other beverages are subject to Tum'ah mi'd'Oraysa evcn if they comprise less than a Revi'is.

Answer #3: Whereas Rabeinu Tam explains that mi'd'Oraysa, beverages require a Revi'is to render others Tamei, whilst mi'de'Rabbanan, they are Metamei others with a Kol-she'Hu.

Extension of Answer #3: According to Rabeinu Tam's explanation, one is forced to say that at this point, it does not occur to the Gemara that a food renders Tamei another food, even mi'de'Rabbanan ...

Extension of Answer #3 (cont.): Since the Gemara needs to establish the case by liquids and mi'de'Rabbanan, rather than by food rendering Tamei food mi'de'Rabbanan.

Implied Question: Yet, despite the fact that a food does not render Tamei another food, even mi'de'Rabbanan, nevertheless it is possible to find a Shelishi ...

Answer: Through wood and frankincense or through liquids, since the decree rendering whatever invalidates T'rumah renders liquids a Rishon, had not yet been issued

Question: Why does the Gemara asks specifically on 'what became Tamei by means of an Av ha'Tum'ah; why not even if it became Tamei through a Rishon or a Sheini, as the Gemara asks later on Rebbi Akiva?

Answer: Because Rebbi Chanina said 'Throughout the days of the Kohanim, implying that this was always the case, even prior to the 'eighteen things' - when they decreed that 'Whatever invalidates T'rumah, renders liquid Tamei to become a Rishon.

Conclusion: Since in the first Perek of Shabbos (Daf 14:) the Gemara establishes 'Food and vessels that became Tamei through liquids; by liquids that became Tamei through contact with hands, and because they decreed that hands render T'rumah Pasul, they declared liquid that touches them a Rishon.

Clarification: The Kashya does not go according to those who say that a food cannot render Tamei another food ...

Clarification (cont.): Since, according to him, the Tana is adding a concession to render it even a Sheini min ha'Torah.

Implied Question: Even though a Shelishi of T'rumah is Metamsi Kodesh just like a Shelishi of Kodesh.

Implied Question (cont.): As we have learned in Maseches Taharos (2:7) 'A Shelishi of all of them (including T'rumah) renders Tamei a liquid of Kodesh and invalidates those who eat Kodesh'.

Answer: Nevertheless, the Ri explains, the touch of a T'vul-Yom is not considered a Shelishi, since even by Kodesh itself, it is not Metamei.

Proof: As we learned in Me'ilah, in Perek Chatas ha'Of (8.) 'A Chatas ha'Of is subject to Me'ilah from the time one declares it Hekdesh; And once the Kohen has performed Melikah, it becomes Pasul through a T'vul-Yom'.

Proof (cont.): And the Gemara extrapolates there 'Pasul, but not Tamei'.

Proof (cont.): And this is also the opinion of Rebbi Akiva later (on Daf 19.).

Question: It is difficult however, as to why the Shelishi of a T'vul-Yom does not make a Revi'i, with a 'Kal va'Chomer' from a Mechusar Kipurim, as Rebbi Yossi concludes regarding a regular Shelishi?

Question (cont.): Why do we not say that if a Mechusar Kipurim, who is permitted to eat T'rumah, renders Kodesh Pasul, the Shelishi of a T'vul-Yom, who is forbidden to eat T'rumah, should certainly render Kodesh Pasul?

Problem: And if, on the other hand, there is a Miy'ut regarding the Shelishi of a T'vul-Yom, then when the Gemara later makes the Kal va'Chomer (according to Rebbi Yossi), why does it not bring a counter-proof from the Shelishi of a T'vul-Yom?

Conclusion: In fact, the Yerushalmi in Maseches Chagigah (Perek 3) asks the Kashya.

Inference: It seems from here, from the Gemara later (Daf 17.) with regard to the liquids of the bei Matbechaya and from various other places, that oil is considered a liquid.

Implied Question: Why does the Mishnah in Taharos (Perek 3,Mishnah 2), after citing Rebbi Meir, who says that oil is always a Rishon, and the Chachamim, who add 'honey', then cites Rebbi Shimon Shezuri, who says 'wine' - specifically wine, whereas the others are not a Rishon (because they are considered solids). And we Pasken like Rebbi Shimon Shezuri?

Answer: The Ri explains that that Sugya is speaking about oil that was originally a solid and that subsequently melted ...

Proof #1: As is implied in the Tosefta ...

Proof #1 (cont.): Where it says 'When did the Chachamim say that oil is a Rishon, when it was originally solidified and then became a liquid', implying that if it was not, then everyone agrees (that it is a liquid).

Proof #2: And this is also implied at the beginning of the third Perek of Taharos (Mishnah 1),where we learned 'Gravy, a bean-stew and milk, if they were initially wet, then they are a Rishon; But if they were initially solid and then melted, they are a Sheini'.

Proof #2 (cont.): Following which Rebbi Meir says 'Oil is always (even if it was initially a solid) a Rishon. And it is in connection with this case that Rebbi Shimon Shezuri makes his statement ...

Conclusion: Whereas our Sugya speaks where the oil was not a solid.

Question: The Ri asks that we should establish the case in the seventh hour, when Chametz is Asur min ha'Torah (adapted from Tosfos Rabeinu Peretz), which one is permitted to now make a Sheini de'Rabbanan, just as one is permitted to make a Shelishi d'Oraysa into a Sheini mi'de'Rabbanan?'

Question (cont.): Whereas Rebbi Yossi, who says 'Einah hi ha'Midah' maintains that one cannot learn Isur from Tum'ah ...

Question (cont.): As Tosfos will later explain according to Resh Lakish in the name of bar Kapara (that one cannot learn Isur from Tum'ah).

Answer: The Ri explains that the Gemara does not want to establish the case by the seventh hour, because 'One burns T'rumah Tehorah together with T'rumah Teme'ah' implies that this is the way that one usually burns one's Chametz, in the sixth hour.

Question: The Ri asks that is is fine according to the opinion that food renders food Tamei (min ha'Torah), that one does not learn an Isur de'Rabbanan in the sixth hour from a P'sul d'Oraysa.

Question (cont.): But according to the opinion that food does not render food Tamei min ha'Torah, why can we not learn that, just as one is permitted to make a Rishon d'Oraysa from a Pasul d'Oraysa, so too, may one make a Sheini de'Rabbanan from an Isur de'Rabbanan?

Answer: The two issues are not comparable; because from the fact that one is permitted to increase a Kilkul d'Oraysa it does not follow that one can do likewise by a Kilkul de'Rabbanan (even if one merely adds only a Kilkul de'Rabbanan).

Conclusion: The Gemara however, will shortly compare the Kilkul of an Isur de'Rabbanan to the Kilkul of a Shelishi de'Rabbanan.

Proof: A proof for this lies in the the fact that Rebbi Yossi, who holds later (16.) that liquids render others Tamei min ha'Torah', in which case the V'lad Tum'ah of Rebbi Chanina is mi'd'Oraysa, declines to learn from it that one is permitted to make an Isur de'Rabbanan, a Sheini mi'de'Rabbanan.

Proof (cont.): Since according to the opinion that holds 'Ein Ochel Metamei Ochel' when one burns it together with Tamei food, it only becomes a Sheini de'Rabbanan.

Question: Having established the case by a V'lad ha'Tum'ah de'Rabbanan, Rebbi Chanina also adds to the ruling of Rebbi Akiva, who permits making a Pasul mi'd'Oraysa a Rishon, we cannot learn that one is also permitted make a Shelishi, a Sheini?

Answer: The Yerushalmi who asks this question, establishes Rebbi Akiva by the T'vul of Tum'as Beis ha'Peras (Tosfos Rabeinu Peretz), which is only de'Rabbanan ...

Answer (cont.): Only the Yerushalmi switches the opinions of Rebbi Yochanan and bar Kapara.