Gemara

Question: (There is no need to decree about certain types of Klei Shetef without an interior, because) mid'Oraisa, a wooden Kli is Mekabel Tum'ah only if it resembles a sack that is made to be moved empty and full!

Answer: Chachamim needed to decree due to Medrasos (Kelim made for people to sit or lie on. They are Mekabel Tum'ah even without an interior.)

Chagigah 26a (Mishnah): During the Regel we warn the Amei ha'Aretz not to touch the Shulchan (for we cannot immerse it later).

R. Eliezer says, all Kelim in the Mikdash must be immersed (after the Regel) except for the gold Mizbe'ach and copper Mizbe'ach, for they are like land;

Chachamim say, because they are plated (this will be explained).

Question: Why are we concerned for the Shulchan? It is a Keli Etz made to be stationary. Such Kelim are not Mekabel Tum'ah! (They are unlike a sack, which can be moved when empty or full.)

Answer: Also the Shulchan is moved empty or full!

Question (Reish Lakish): "Al ha'Shulchan ha'Tahor" implies that the Shulchan is Mekabel Tum'ah. However, it is a Keli Etz made to be stationary, which is not Mekabel Tum'ah!

Answer: The verse teaches that (It is moved;) they would lift up the Shulchan on the festival to show the Lechem ha'Panim.

Question: The Shulchan should be Mekabel Tum'ah because it is plated!

Answer: The Shulchan is an exception, for the Torah calls it a Keli Etz - "ha'Mizbe'ach Etz..."

Shabbos 83b (Mishnah): "Derech Aniyah v'Lev Yam" equates a boat to the sea. Just like the sea is Tahor, also a boat.

(Beraisa - Chananyah): We learn from a sack. Just like a sack can be moved when empty or full, also everything (of wood is Mekabel Tum'ah only if it) can be moved when empty or full. This excludes a boat.

Question: What is the difference between the Mishnah and Chananyah?

Answer #1: They argue about a boat of earthenware. If we learn from "Aniyah v'Lev Yam" it is Tahor. If we learn from a sack, it is Tamei. (The Hekesh does not apply to Klei Cheres).

Answer #2: They argue about a (small) boat that goes on the Yarden. If we learn from "Aniyah v'Lev Yam", it is Tahor. If we learn from Sak, it is Tamei. (It can be moved even when full);

(R. Chanina ben Akiva): Sefinas ha'Yarden is Tamei because they load it on the dry land and take it to the water.

Rishonim

Rambam (Hilchos Mishkav u'Moshav 11:11): On Motza'ei Yom Tov after the Regel all the Kelim in the Mikdash require Tevilah and ha'Arev Shemesh, except for the gold Mizbe'ach and copper Mizbe'ach, because their plating is Batel to them.

Kesef Mishneh: This is like Chachamim, according to the second answer, for the Mishnah connotes like it. Also, the latter answer is (normally) primary.

Tosfos (Chagigah 26b DH Kli): The 40 years that Bnei Yisrael were in the Midbar, the Shulchan was moved. Why was a verse needed to teach that it is Mekabel Tum'ah? R. Elchanan answered that the verse teaches about the Shulchan in the Beis ha'Mikdash, and when the Mishkan was set up in Nov, Giv'on and Shilo, for then it was stationary. I disagree. Since it was Mekabel Tum'ah when it used to be moved, even when it was (permanently) set up in the Beis ha'Mikdash it is still Mekabel Tum'ah! Rather, it is not considered a Kli that is moved, since it was moved only along with other Kelim.

Mishneh l'Melech (DH u'Mah): The Shulchan was Mekabel Tum'ah because they would lift it during the festival to show the Lechem ha'Panim to Olei Regalim. Even though it was covered with gold and we hold that plated Kelim are not Mekabel Tum'ah, the Torah called it "Etz". (Therefore, it is like a regular wooden Kli.)

Rambam (Hilchos Kelim 3:1): Any Keli Etz made to be stationary, even if it can hold only a tiny amount, is not Mekabel Tum'ah at all, i.e. mid'Oraisa or mid'Rabanan. Any Keli made to be moved when empty or full, even if it holds 100 Sa'im, and even if it has a base, it is Mekabel Tum'ah like other Kelim that hold things. If a Stam Keli Etz has a base to sit firmly on the ground without rolling easily, if it holds 40 Sa'im of liquid, which is like 60 Sa'im of dry goods (since they can be heaped on top), it is not Mekabel Tum'ah at all, because the Chazakah is that it is made to be stationary. These matters are a tradition. Just like a sack is moved when empty or full, also Klei Etz are Mekabel Tum'ah only if they are moved when empty or full. This excludes a Keli made to be stationary.

Kesef Mishneh: Rashi (26b) explains that a Hekesh teaches that Klei Etz are Mekabel Tum'ah only if they are moved empty and full, like a sack. People do not move a Kli that holds 40 Sa'im when it is full, for it would break.

Rebuttal (of Rambam - Ra'avad): What is his source? He must learn from the Shulchan and Menorah. Even though they do not hold 40 Sa'im, the Gemara said that they should be Tehorim because they are stationary. We cannot learn from them, for it is forbidden to move them! The Gemara said that any Kli Etz made to be moved empty and full is Mekabel Tum'ah, even if it holds 100 Kor (3000 Sa'im). We learn from Sefinas ha'Yarden (a boat of the Jordan river). Perhaps it is not like the Rambam holds, rather, since Sefinas ha'Yarden is normally lowered into the water only when it is full. In Kelim (15:1), R. Yehudah says that a kneading bowl of tanners and a small boat, even though they hold 40 Sa'im, are Tamei. They are made to be moved only with what is inside. Other Kelim are Tamei only if they do not hold 40 Sa'im. R. Meir and R. Yehudah argue only a Ba'al ha'Bayis' kneading bowl that holds 40 Sa'im. R. Yehudah is Metaher even though sometimes they carry it full to a big oven. The Mishnah says that we are Metamei when it is made to be moved only with what is inside, but if sometimes it is moved full, and sometimes empty, it is Tahor. We do not follow the Chazakah.

Kesef Mishneh: What is the Isur to move the Menorah or Shulchan? Even if it were Asur, the Hekesh is Metaher whatever is not normally moved full and empty. It need not be due to Isur. We exclude a Kli that holds 40 Sa'im for this reason, even though it is not forbidden to move it! It is not a proper rebuttal to say 'perhaps it means...' There is no proof for the Ra'avad's words. The Rambam concludes that Klei Etz are Mekabel Tum'ah only if they are moved when empty or full, i.e. even if they hold 100 Sa'im.

Mishneh l'Melech: Rashi and Tosfos in Chagigah hold that a stationary Klei Etz is Mekabel Tum'ah if it is plated. The Ra'avad and R. Shimshon agree. The Rambam holds oppositely, that even if it is not stationary and it can hold things, if it is plated it is not Mekabel Tum'ah. The plating is Mevatel the Kli, and the plating is not Mekabel Tum'ah. I am unsure about a Klei Etz made to be stationary and it is designated for Medras. Is it Mekabel other Tum'os? We have a general rule that anything that is Mekabel Tum'as Medras is Mekabel other Tum'os. Or, perhaps this rule is only for Klei Etz that do not hold anything.

Perush ha'Mishnayos (Kelim 30:4): A glass chest, box, or tower is not Mekabel Tum'ah if it holds 40 Sa'im, as if it were of wood.

Tosfos (Shabbos 83b DH Nilmedah): A boat is not special for Medras. Even though people constantly sit on it, it is primarily for merchandise. (If one sits on it,) we say 'get up, so we can do our labor!' If a boat were special for Medras, we would not learn from a sack, for Medrasos were not equated to a sack.

Tosfos (DH Le'afukei): A boat is not moved when full. Moving in the sea is not called moving, since primarily the water takes it.

Tosfos (Shabbos 44b DH Muchni): Rashi says that we discuss a carriage in which people ride. The Ri disagrees. If Medras applies to it, the size would not matter, for it is not equated to a sack. We would not need that it is moved full and empty. This is clear from Bechoros. We asked that a Kli Shetef without an interior is Tahor, for it is unlike a sack. We answered that we discuss Kelim proper for Medras (which are not equated to sack). On 84a, we say that a chest of 40 Sa'im is not Mekabel Tum'ah. It does not have a hole in the side. One that had a hole is proper for Medras, so it is Tamei even if it holds 40 Sa'im.

Tosfos Yom Tov (Kelim 24:4): The verse "v'Chol Kli Etz..." discusses Tum'as Mes and Sheretz. Only for these, Klei Etz are equated to sack. Anything proper for Medras has Tum'as Mes. We learn from a Kal va'Chomer from jars with narrow openings (they receive Tum'as Mes, even though a Zav is not Metamei them). However, a Mishnah (20:1) says that if a Kli could hold something and was broken and not it cannot hold, it became Tahor from other Tum'os, even though it still has Medras. We do not apply 'anything proper for Medras has Tum'as Mes.' That rule does not apply to what broke. This is according to the Bartenura and R. Shimshon. The Rambam says that Peshutei Klei Etz are Mekabel Tum'ah mid'Rabanan. He did not say so about Klei Etz that hold 40 Sa'im. He must explain that Bechoros 38a teaches only about Peshutei Klei Etz, but not about Kelim that hold 40 Sa'im. The Torah excluded both of them from Tum'ah. The Gemara taught that the former have Tum'ah mid'Rabanan. We cannot extrapolate to the latter.

Rashba (Teshuvah 1:195): A wooden ladder is Mekabel Tum'ah if it is portable, like a sack. The side beams have holes to hold the rungs. Therefore, one may not use it for Sechach.