How so? [If] an olive-pressing basket was placed on top of a pit or a cistern that is inside a house, [the contents of the pit or cistern] remain tahor. [However,] if an olive-pressing basket was placed on top of either a well that is level [to the floor of the house] or a broken basket, [the contents of the well or the basket] become tamei. [On the other hand,] if a flat board or a kneading board without sides [was placed on top of either a well that is level to the floor of the house or atop a broken basket, the contents] remain tahor. This is because utensils combine with the walls of a structure to curtail [tumah] only when there are walls. How high must the wall be [to block tumah]? One handbreadth. [However, if] half of a handbreadth is from [a wall] and the other half of a handbreadth is from [the olive-pressing basket], it is not considered to be a wall. [It is only a wall] when one of them is a handbreadth by itself.

Just as they curtail [tumah] when they are inside, so do they curtail [tumah] when they are outside. How so? An olive-pressing basket is placed on pegs outside [a house. If] there is tumah underneath the olive-pressing basket, utensils inside it re-main tahor. If [the olive-pressing basket is placed on pegs next to] the wall of a courtyard or the wall of a garden, it does not curtail [tumah]. A beam is placed between two walls, and a pot is suspended from [the beam]. [If] there is tumah beneath [the beam], utensils inside the pot are ruled tahor by R’ Akiva, but they are ruled tamei by the Sages.

Man and utensils become roofs to convey tumah, but not to maintain something as tahor. How so? Four [people] are holding a slab of stone. [If there] is tumah below [the slab], the utensils on top of it become tamei. [If] there is tumah above it, the utensils underneath it become tamei. R’ Eliezer declares [them] tahor. [The slab] is placed on four utensils, even utensils made of dung, stone, or unbaked clay. [If] there is tumah underneath it, utensils on top of it become tamei. [If] there is tumah above it, the utensils underneath it become tamei. [The slab] is placed on four stones or on a living creature. [If] there is tumah underneath [the slab], the utensils on top of it remain tahor. [If] there is tumah above it, the utensils underneath it remain tahor.

Corpse bearers that will be passing under a portico, and one of them shut the door and closed it with the key — if the door can remain closed by itself, [the house] re-mains tahor, but if not, [the house] becomes tamei. A similar case would be where a barrel of dried figs or a box of straw was placed in a window. If the dried figs or straw can remain in place by themselves, [the contents] remain tahor, but if not, everything becomes tamei. A house was partitioned with jugs that were plastered with clay. If the clay can remain [in place] by itself, [the other side of the house] remains tahor, but if not, it becomes tamei.