Sukkah, Chapter 1, Mishnah 7. In the previous mishnah we studied the dispute between Rabbi Yehudah and Rabbi Meir regarding boards - planks whose width is between three and four handbreadths: Rabbi Yehudah held that one may use them as sechach, while Rabbi Meir held that one may not, because such a covering resembles sitting under a roof far too closely.
The text of the Mishnah:
"Tikrah she'ein aleha ma'azivah" - a ceiling made of boards alone, with no layer of plaster or mortar on top binding the boards to one another. We will explain the mishnah according to the opinions that it is speaking of boards whose width is between three and four handbreadths, in line with the dispute between Rabbi Yehudah and Rabbi Meir in the previous mishnah.
Even though Rabbi Yehudah permitted in the previous mishnah making a sukkah out of boards of this width, here the case is different: these boards were not placed there originally for the sake of a sukkah, but served as a ceiling and a roof. Even though they are not joined to one another with mortar, since they function as a roof one must perform some action with them so that they become fit to serve as sechach. Otherwise there is the problem of "ta'aseh v'lo min he'asui" (it must be made, and not come about on its own), since they were planned and made for the sake of a house and not for the sake of a sukkah.
Two possible actions are under discussion:
Loosening (pikpuk): lifting the boards and setting them back down, thereby placing them for the sake of a sukkah and removing the problem of "ta'aseh v'lo min he'asui."
Removing every other board: taking out every second board and placing valid sechach in its place, sechach that was set there from the outset for the sake of a sukkah.
The opinions of the Tannaim:
Beis Shammai (according to Rabbi Yehudah): "mefakpek v'notel achas mibeinasayim" - both actions are required together. In their view it is not enough for the boards to be placed for the sake of a sukkah; there must also be ordinary valid sechach there, and not sechach made of boards that were designed to serve as a roof, for otherwise the covering resembles a roof far too closely.
Beis Hillel (according to Rabbi Yehudah): "mefakpek o notel achas mibeinasayim" - either one of the two actions suffices. Either he lifts the boards and sets them down for the sake of a sukkah, thereby removing the problem of "ta'aseh v'lo min he'asui," or he takes out every second board and places valid sechach in its place.
Rabbi Meir: "notel achas mibeinasayim" - in his view one must specifically take out every second board and place valid sechach there, and loosening alone does not help. For according to him, beyond the problem of "ta'aseh v'lo min he'asui" - that the boards were not made for the sake of a sukkah - even if he were to lift the boards and set them down for the sake of a sukkah, this would still not be a valid sukkah.
In summary: in this mishnah we learned about a ceiling with no plaster on top of it, made of boards that were placed there to serve as a roof and not for the sake of a sukkah, and how it can be made fit to serve as a sukkah: according to Beis Shammai, through both actions together - loosening and removing every other board; according to Beis Hillel, one of them suffices; and according to Rabbi Meir, one must remove every other board and place valid sechach there, and loosening alone does not help.