1)

(a)The Mezuzah that Rav Huna requires in connection with the skylight leading from the ground floor to the first floor - refers to the door that opens to the enclosed staircase which leads up to the skylight.

(b)If there are two doors, he requires two Mezuzos. The second door - opens to the top of the enclosed staircase, which leads down to the ground-floor.

(c)The bottom door prevents the upstairs residents from entering the ground-floor without permission, whilst the top one prevents the ground floor residents from doing the same upstairs.

(d)Rav Papa extrapolates from Rav Huna that - if a room has four doors - all of them require a Mezuzah.

2)

(a)In answer to the question that this ruling is obvious - we establish the case where one of the doors is used regularly, whilst the others are not (see Shitah Mekubetzes 3).

(b)To reconcile this ruling with the case we learned earlier (in connection with Rav Huna's Shul door), that an entrance that is rarely used is Bateil to one that is used frequently - we differentiate between two doors, where one door can become Bateil to another, and four, where three doors cannot become Bateil to one.

(c)Alternatively, 'Halach acher ha'Ragil' (given as the reason in the case of Rav's Shul door) comes to preclude - the Shul door of Rebbi, which was a private doorway, but not a room that requires a number of doors for the many people who use it (even if, after a time, the people begin to use it less frequently, such as in our case).

3)

(a)Ameimar - requires a corner door to have a Mezuzah.

(b)When Rav Ashi queried him about the fact that it only has one door-post, he replied - that the adjacent wall serves as the second door-post.

(c)When Rav Papa (or Rav Mari) arrived in Shmuel's house, he found - that it possessed only the left door-post.

(d)He dismissed the suggestion that Shmuel held like Rebbi Meir - who requires a Mezuzah on a room with only one door-post ...

(e)... because even Rebbi Meir will agree that if it is the right-hand door-post that is missing, the house is Patur from Mezuzah.

4)

(a)The Beraisa learns from the Pasuk in Va'eschanan (in connection with Mezuzah) "Beischa" - 'Derech Bi'ascha', implying the right-hand side ...

(b)... because when a person enters a house, he generally enters with his right foot (as one usually begins walking with the right-foot).

(c)Rabah bar Ula learns this from the box that Yehoyada ha'Kohen affixed to the right hand side of the Azarah as one entered, on the north wall in the vicinity of the Mizbe'ach.

5)

(a)Rebbi Meir in a Beraisa requires a Mezuzah on a room with only one door-post. The Chachamim - exempt it.

(b)On the one hand ...

1. ... the Rabbanan learn from the word "Mezuzos" (plural) that a door is only Chayav Mezuzah if it has two door-posts; whereas on the other hand ...

2. ... according to Rebbi Yishmael in another Beraisa, Rebbi Meir learns from the repetition of the word "Mezuzos" that - even one door-post is Chayav (based on the principle Ein Ribuy Achar Ribuy Ela Lema'et).

(c)Rebbi Akiva there maintains that this is not necessary, because he extrapolates from the Pasuk in Bo (in connection with the blood of the Korban Pesach) "al ha'Mashkof ve'al Sh'tei he'Mezuzos" that - wherever the Torah does not add a number, "Mezuzos" (even when it is written in the plural) means one door-post.

6)

(a)The Beraisa learns from the Gezeirah-Shavah "u'Chesavtam" (by Mezuzah) "Ve'chasav lah" (by Get) - that a Mezuzah must be written (not directly on the door-post, but) on a Seifer (a piece of parchment), and then affixed to the door-post.

(b)The alternative Pasuk for the Gezeirah-Shavah from which we will learn that the Mezuzah must be written directly on the door-post is the Pasuk in Ki Savo "Ve'chasavta al ha'Avanim" (in connection with Har Gerizim and Har Eival).

(c)And the reason that we opt to learn it from Get, and not from the stones is - because the latter were merely a Hora'as Sha'ah (a momentary ruling).

(d)And from the Pasuk in Yirmiyah "Va'yomer lahem Baruch, mi'Piv Yikarei ... va'Ani Kosev al ha'Seifer bi'Deyo" we learn that - both a Get and a Mezuzah must be written with ink.

7)

(a)In reply to Rav Acha b'rei de'Rava Kashya how a 'Gezeirah-Shavah' can possibly change the meaning of the words "al Mezuzos" (implying directly on the door-post), Rav Ashi replied that - "u'Chesavtam", followed by "al Mezuzos" implies that first it must be written with a proper script ('Kesivah Tamah'), and then placed on the door-post.

(b)And when he asked him further why we then need the Gezeirah-Shavah, he replied that - without it, we would have thought that one engraves the words on a stone (as this too, is considered Kesivah Tamah) which one then affixes to the door-post.

(c)We query our Mishnah (which rules that even one letter is Me'akev) 'P'shita' - to which Rav Yehudah Amar Rav initially answers that - the Tana is referring to the Kutzo shel Yud (the tip of the 'Yud').

(d)Since however, that too is obvious, we answer with another statement of Rav Yehudah Amar Rav, where he renders a letter Pasul - if it is not surrounded by parchment (as we explained in our Mishnah) even though it is written correctly.

8)

(a)Rebbi Yishmael in a Beraisa learns the four Parshiyos of Tefilin from the three times that the Torah writes "le'Totafos". Four Parshiyos and not six, in spite of the fact that "le'Totafos" is plural - because two of them are written without a 'Vav', implying the singular (le'Totefes).

(b)Rebbi Akiva maintains that this is not necessary - because 'Tat' means two in Kaspi, and 'Pas', in African (see Shitah Mekubetzes 1).

(c)The Tana in another Beraisa learns from the Pasuk in Bo "u'le'Zikaron bein Einecha" that - one writes the four Parshiyos on four pieces of K'laf (parchment), which one places into four compartments made out of one piece of K'laf (Zikaron Echad) ...

(d)... and not into four compartments made of four pieces of K'laf.

9)

(a)According to Rebbi, if one writes all four Parshiyos on one piece of K'laf - the Tefilin are nevertheless Kasher.

(b)And the space that Rebbi nevertheless requires in between the Parshiyos, one achieves - by making three cuts into the top of the K'laf to form four fingers (thereby separating the four Parshiyos), and then placing each finger (each Parshah) into one of the four compartments.

(c)The Chachamim do not consider this necessary - though they do require each Parshah at least to be bound with an independent thread (See Shitah Mekubetzes).

(d)The Beraisa concludes ve'Im Ein Charitzan Nikar, Pesulos - meaning that if, one cannot see from the outside that the Bayis comprises four compartments, the Tefilin are Pasul.

10)

(a)The Tefilin shel Yad are written - on one piece of parchment.

(b)Rebbi Yehudah in a Beraisa permits writing it on four pieces, on condition - that one sews or glues them together before placing them inside the Bayis.

(c)And he learns this from the Pasuk "Vehayah l'cha le'Os al Yadcha" - implying that the Tefilin shel Yad must be one sign (and not four) on the inside (which is 'for you'), just as they are one sign on the outside (which others see).

(d)Rebbi Yossi maintains that - it is not necessary to sew or glues them together.

11)

(a)According to Rebbi Yossi - Rebbi Yehudah b'Rebbi concedes that someone who has two pairs of Tefilin shel Rosh, but no Tefilin shel Yad - may convert one of them into Tefilin shel Yad by merely covering the outside with a piece of skin.

(b)By 'Rebbi Yehudah b'Rebbi', he meant - Rebbi Yehudah the Chacham.

(c)In spite of the fact that it is in this very point that they argue, Rava explains Rebbi Yossi's statement to mean that - Rebbi Yehudah relented from his original stance.

12)

(a)Rav Chananyah in the name of Rav - permits converting ...

1. ... Tefilin shel Yad into shel Rosh ...

2. ... but not vice-versa ...

(b)... because the Tefilin shel Rosh possess a higher level of Kedushah than the shel Yad (and it is forbidden to downgrade Kedushah).

(c)This distinction is created by virtue of the fact that - the majority of Hash-m's Name 'Shakai' is to be found on the shel Rosh (the 'Shin' on the Bayis, and the 'Daled' on the strap), whereas only the 'Yud' appears on the (strap of) the shel Yad.

(d)To reconcile Rebbi Yossi's previous statement with that of Rav Chananyah in the name of Rav, we establish it ...

1. ... by new Tefilin that have never been used, assuming that we hold Hazmanah La'av Milsa hi (in which case until the Tefilin have been worn, they (the Batim) have no Kedushah, whereas ...

2. ... according to those who hold Hazmanah Milsa hi, where the owner stipulated at the outset that he would be permitted to use the shel Rosh as the shel Yad, should this become necessary,.

13)

(a)The Beraisa requires 'Kadeish' and 'Vehayah ki Yevi'acha' to be on the right side of the Tefilin, and 'Sh'ma' and 'Vehayah im Shamo'a' on the left. Abaye reconciles this with the Beraisa, which says the opposite - by establishing the former from the point of view of the reader; and the latter, of that of the wearer.

(b)The Tana concludes ve'ha'Korei, Korei ke'Sidran meaning that - seeing as 'Sh'ma' is on the inside, next to 'Vehayah ki Yevi'acha', this follows the order in which they are written in the Torah (see Tosfos DH 've'ha'Korei').