QUESTION: The Mishnah (11a) states that Sechach must be comprised of a material that cannot become Tamei and that grows from the ground (Gidulei Karka). Rebbi Yochanan says that this requirement is derived from the verse, "b'Aspecha mi'Garnecha umi'Yikvecha" -- "[You shall make the festival of Sukos for seven days] when you gather in from your threshing floor and from your winepress" (Devarim 16:13), which teaches that Sechach must be made from material similar to the remains that are left over from the threshing and wine pressing processes ("Pesoles Goren v'Yekev").

Rav Chisda says that this requirement is derived from a verse in Nechemyah (8:15), which teaches that the Sechach must be similar to the "branches of myrtle" (which cannot become Tamei and are Gedulei Karka).

According to both opinions, why may Sechach be made from any type of wood other than the type mentioned in the respective verses? According to Rebbi Yochanan, only grain stalks or vine branches ("Pesoles Goren v'Yekev") should be valid Sechach. According to Rav Chisda, only the specific types of wood mentioned in the verse in Nechemyah should be valid Sechach (the wood of olive, pine, myrtle, and palm trees). What indication is there in the verses to permit Sechach from natural products that are similar to the types mentioned in the verses?

The answer is that any guideline for valid Sechach derived from the verses must have some logical basis. It is logical to derive from the verse that Sechach must be a product of nature and not a processed item, since that is the type of covering normally used to make shade for a temporary dwelling. Accordingly, the verse excludes anything that can be Mekabel Tum'ah (since such an item is processed), anything that does not grow from the ground, and a live animal (since such items are not normally used to make shade). However, with regard to different types of wood, there is no logical reason to say that one type may be used any more than another, as the Torah does not specify that any specific type of wood must be used for Sechach.

The RITVA (11b) questions this approach. RASHI (11a, DH Pesulah) writes that the source for the requirement that Sechach be detached from the ground is the verse cited by Rebbi Yochanan. Just as the remains left over from the threshing and wine pressing processes ("Pesoles Goren v'Yekev") are not attached to the ground, Sechach also must not be attached to the ground ("Mechubar"). What, though, is the logical basis to derive from "Pesoles Goren v'Yekev" that Sechach that is Mechubar may not be used? On the contrary, if a natural product must be used, it is logical that something that is attached to the ground is more fit for Sechach than something that has been detached, because it is more natural. It seems illogical to derive from the verse that only a detached natural product may be used. (There is an error in the older printings of the Ritva, in which the name "Rav Chisda" appears instead of the word "Rachmana," which has caused considerable confusion about the Ritva's intention. The text of the Ritva has been corrected in the Mosad ha'Rav Kook edition of the Chidushei ha'Ritva.)

ANSWER: Because of this question, the RE'AH and RITVA disagree with Rashi and conclude that the Pesul of Mechubar is derived from a different source. It is derived from the principle of "Ta'aseh," which teaches that one must perform a positive action to make Sechach. When one places branches that are still attached to the ground (or tree) onto the Sukah, he performs no action; rather, he merely waves the branches from one place to another. (This differs from the Pesul of "Ta'aseh v'Lo Min he'Asuy," which describes what type of action is necessary: the action which creates a valid Sukah must be the placing of the Sechach and not a later action (such as the cutting of the Sechach from its source).)

When Rashi says that Sechach that is Mechubar is invalid because it does not fall into the category of "Pesoles Goren v'Yekev," his intention might be to explain as the Ritva does. Rashi might mean that the Halachic difference between an object that is Mechubar and one that is not is that in the case of an object that is Mechubar, one does no positive action to make the Sechach. Rashi learns from "Pesoles Goren v'Yekev" that an action must be done to the Sechach itself in order to make the Sukah valid.

OPINIONS: Rebbi Yochanan rules that strands of unprocessed flax may be used as Sechach. If, however, the strands have been pressed and combed, then they may not be used as Sechach.

Since flax strands are natural products that grow from the ground, why may they not be used as Sechach when they have been pressed and combed?

(a) RASHI (DH Sachachah) explains that the Gemara refers to strands of flax that have been bleached. Bleached strands are able to become Tamei with Tum'as Nega'im according to one opinion (Rebbi Yehudah, Nega'im 11:8) even though they have not yet been spun.

(b) TOSFOS (DH b'Anitzei) writes that flax strands that have not been spun are not Mekabel Tum'ah, even Tum'as Nega'im, according to everyone. (When Rebbi Yehudah in Nega'im says that they are Mekabel Tum'ah once they have been bleached, he refers to after they have been spun.)

Tosfos explains instead that since the strands are near a state in which they will be Mekabel Tum'ah (since they have been prepared to be spun), the Rabanan decreed that they may not be used as Sechach. Tosfos adds that they are considered unfit for Sechach only according to the opinion that maintains that flax strands do not need to be bleached in order to be Mekabel Tum'ah. According to that opinion, strands that have been prepared to be spun are near the stage at which they will be Mekabel Tum'ah. (In contrast, according to Rebbi Yehudah who says that flax strands must be bleached in order to be Mekabel Tum'ah, strands that have been prepared to be spun are not even near the stage at which they will be Mekabel Tum'as Nega'im).

(c) The RAMBAM (Hilchos Sukah 5:4) writes that the reason why pressed and combed flax strands may not be used as Sechach is because their form has changed as a result of being pressed and combed. They no longer resemble Gedulei Karka, objects that grew from the ground.

(d) The RA'AVAD argues with the Rambam and explains that the reason why flax strands may not be used as Sechach is because they are fit for other forms of use in their present state; they may be used as stuffing for pillows and sheets. Since pillows and sheets are Mekabel Tum'ah, the stuffing is also Mekabel Tum'ah. (He appears to rely on the Mishnah in Kelim (17:13) which says that objects that are not Mekabel Tum'ah by themselves nevertheless can be Mekabel Tum'ah when they are sewn to other objects that are Mekabel Tum'ah).