1)

(a)Our Mishnah permits clearing out water-pits that became clogged -up with stones. Rebbi Yakov Amar Rebbi Yochanan qualifies this ruling - by confining it to where it is performed on behalf of a private person. But where it is for the needs of the community, he permits even digging a pit from scratch.

(b)We ultimately explain the Beraisa ...

1. ... 'Chotetin Boros, Sichin u'Me'aros shel Yachid, v'Ein Tzarich Lomar shel Rabim' - to mean that one may clear out the stones from private water-pits etc. that the owner needs; and it goes without saying, public ones, which may even be dug from scratch, if the public need them.

2. ... 'Ein Chofrin Boros, Sichin u'Me'aros shel Rabim, v'Ein Tzarich Lomar shel Yachid' - that one may not dig from scratch public water-pits etc. which are not needed; and it goes without saying, private ones, where even clearing out the stones is forbidden if they are not needed.

(c)We have just learned that clearing out stones is permitted in certain cases even when digging a pit is forbidden. The Tana of the Beraisa compares ...

1. ... filling a pit that has already been dug, with water - to clearing out the stones.

2. ... filling in cracks and strengthening them with lime - to digging a pit.

2)

(a)Rav Ashi extrapolates from our Mishnah 'Osin Kol Tzorchei Rabim' which is otherwise superfluous - that one is permitted to dig water-pits on behalf of the community (vindicating Rebbi Yochanan).

(b)We refute the suggestion that 'Osin Kol Tzorchei Rabim' comes to include general communal needs such as the removal of thorns, road repairs and rectifying the Mikva'os, listed in the Beraisa - on the grounds that the Mishnah has already listed these specifically, so it is not necessary to include them.

(c)The Tana of the Beraisa learns from the Pasuk "v'Hayah Alecha Damim" - that if Beis-Din do not see to public needs, such as clearing away thorns from the streets, then they are responsible from any ensuing accidents.

3)

(a)Rebbi Shimon ben Pazi says - interprets the Pasuk "v'Ra'ah Etzem Adam u'Banah Etzlo Tziyun" as a hint for Tziyun Kevarim (the obligation to mark unknown graves).

(b)Before Yechezkel ha'Navi came upon the scene - they knew about Tziyun Kevarim, because it is Halachah l'Moshe mi'Sinai (which Yechezkel merely supports with a Pasuk).

(c)Yechezkel also supported with a Pasuk the Halachah (l'Moshe mi'Sinai) - that a Kohen Arel Basar (who is uncircumcised) or an Arel Lev (who serves idols) is disqualified from serving in the Beis Hamikdash.

(d)Others learn Tziyun Kevarim from the Pasuk in Tazri'a "v'Tamei Tamei Yikra". From the second "Tamei" we learn - that the Metzora should publicize his pain, thereby encouraging others to pray for him.

4)

(a)Other Amora'im learn Tziyun Kevarim from "v'Lifnei Iver ... ", "v'Amar Solu Solu Panu Derech" or from "Harimu Michshol mi'Derech Ami"; from "v'Hoda'ta Lahem es ha'Derech Yelchu Vah", v'Hizartem es Bnei Yisrael mi'Tum'asam" or from "u'Shemartem es Mishmarti". The final Derashah is from the Pasuk in Tehilim "v'Sham Derech Ar'enu b'Yesha Elokim". Rebbi Yehoshua ben Levi also learns from this latter Pasuk - that those people who live with a Cheshbon ha'Nefesh (who reckon the loss caused by performing a Mitzvah against the potential gain, and the gain caused by sinning against the potential loss), will merit Divine salvation.

(b)Rebbi Yanai quoted this Pasuk regarding an astute Talmid of his - who would also ask him Kashyos on his Derashos during the week, but not on Shabbos of Yom Tov, when a lot of people came to hear the Derashah, and asking Rebbi Yanai a Kashya which he might not have perhaps been able to answer, would have caused him much embarrassment.

5)

(a)They would not mark (with lime) a k'Zayis of flesh or a bone exactly the size of a barley that came from a corpse (in spite of the fact that it is Metamei b'Ohel [see Tos. DH 'Etzem ... ']) - because it was only a matter of a short time until it would shrink to less than a k'Zayis (and no longer be Metamei).

(b)Chazal did not decree that it should be marked for that short time - because, they figured, it was better for people to walk over it during that short period, discover what they had done and be obligated to burn Terumah and Kodshim that became Tamei as a result, rather than that the bone should be marked, with the result that, from then on, people who walked over it, would continue to burn Terumah and Kodshim, thinking that the bone was still the size of k'Zayis, even after it no longer was.

(c)Besides the spinal cord - they would also mark the skull of a corpse, both of which are Metamei b'Ohel, even though they do not comprise the majority of the corpse.

(d)A minority of large bones that made up the majority of the corpse's volume would be marked - as would the majority (in number) of the corpse's bones, even if they did not make up the majority in volume.

6)

(a)They would mark the location of the corpse (with lime) - when it was Safek Tamei (which will be described later), but not when it was Vaday Tamei.

(b)They would place the lime - close to the spot where they believed the Tum'ah to be.

(c)They would not place it ...

1. ... on the Tum'ah itself - in order to avoid the possibility of someone walking over it by the time he noticed the marker.

2. ... far from the Tum'ah - in order not to render more of Eretz Yisrael inaccessible than was necessary.

7)

(a)Two of the three cases of Safek that would be marked were 'Sechachos' and 'Pera'os'.

1. ... 'Sechachos' - are branches of a tree that is known to overhang a grave, but not which branch (see also Tosfos DH 'Ilan').

2. ... 'Pera'os' - are stones that protrude from a stone wall, under the same circumstances as the branches of a tree.

(b)The third case of Safek is that of a Beis ha'Pras. Rav Yehudah Amar Shmuel, who permits blowing one's way through a Beis ha'Pras in order to bring the Korban Pesach, and Ula, who is quoted as saying that a Beis ha'Pras that has been 'threshed' is Tahor (both of whom clearly hold that there is no Din of Tum'as Ohel by a Beis ha'Pras) - are speaking about a field in which a grave was plowed up (in which case, there may well be no Tum'ah at all); whereas we are speaking about a field which is known to contain a grave, but not its exact location (so that there is definitely Tum'ah there (since that that too, is called a 'Beis ha'Pras').

(c)We know that a field in which a grave is lost is called a Beis ha'Pras - because the Mishnah in Ohalos includes it in its list of three different categories of Beis ha'Pras.

(d)The third category of Beis ha'Pras described in the Mishnah in Ohalos is 'a Sadeh Bochin' - a field next to a town where a corpse was brought to be buried. Those who had brought him from the town where he had died would hand him over to those who would wash and bury him. Sometimes, it appears, due to the long trek from one town to another, limbs might fall off from the corpse, which each group, believing that the second group would tend to it, would leave lying there (creating the Safek Beis ha'Pras). The field is called a 'Sadeh Bochin' - because as the corpse was being handed from one group to the other, it was common for all of them to burst into tears.

8)

(a)The Tana Kama of the Beraisa explains that if one comes across a marked field with trees, it is a plowed field (because they would have to plow it on account of the trees) - whereas one without trees - is considered a field where a grave has been lost (but not plowed up).

(b)Rebbi Yehudah says - that we can only know whether the field was plowed or not if we hear it from an elder or from a young Talmid-Chacham.

(c)It appears from the Tana Kama that even a field in which a grave was dug also needs to be marked. To reconcile this with the Sugya that we just learned (which assumes that it does not) - Rav Papa establishes the case there when the field was first marked after the grave became lost, but plowed only afterwards (due to the trees that grew in it).

(d)To answer the question how we know that a grave was dug up, since the trees are on the inside (which was plowed) and the Tum'ah that was lost, on the outside (which was not), we cite Ula elsewhere - who establishes a certain case where the trees are situated right next to the street, and one does not generally bury people in the public street. Consequently, the grave must have been in between the trees, which is where they plowed.

9)

(a)We then ask that perhaps the Tum'ah was on the inside (beyond the trees and not between them) and the trees on the outside. We first answer that it speaks 'bi'Mesuvachin' - meaning that the trees were not all planted in one straight row, but were scattered round the field, in which case the entire field will have been plowed because of them.

(b)Alternatively, it cannot speak when they marked the far side of the trees, and the grave was on the near side - because, as we have already learned, one does not place the marker far from the Tum'ah.

(c)Rebbi Yehudah in the Beraisa, maintains that whether a marked field contains a plowed grave or a lost one can only be determined by an elder or by a young Talmid-Chacham. Abaye derives from Rebbi Yehudah's statement - that when there is a Talmid-Chacham in town, all the major issues that concern the town fall under his jurisdiction.