Ohalos, Chapter 9, Mishnah 2. This chapter deals with a kaveres, a beehive, that is lying in the doorway of a house. The mouth of the beehive faces outward, toward the street, while the closed end of it lies inside the house. That closed end is not entirely sealed: a beehive has two small holes through which the bees come and go, and here they are stopped up with straw.
What sets this mishnah apart from what precedes it is a single measurement: the hive's elevation. Earlier the kaveres sat directly upon the floor, or was lifted by less than a handbreadth, so the gap beneath it was too shallow to rank as an ohel, and tumah could move only vertically, upward and downward. Here the kaveres stands a full tefach above the floor. The gap below now counts independently as an ohel, and once it does, the tumah is no longer confined to a narrow shaft; it fills the hive's entire length.
The Words of the Mishnah
"Haysah gevohah min ha'aretz tefach": the hive stood a handbreadth above the floor. The mishnah then presents three possible locations for a kezayis of tumah. "Tumah tachteha": the tumah lies in the space below the hive. "O babayis": alternatively, it lies within the house. "O al gabah": or it sits upon the hive's upper surface. For all three of these, the ruling is "hakol tamei, ela tochah": everything contracts tumah, every keli in the house and in the vicinity of the hive, with a single exception, namely the hive's interior. Then comes the final possibility: "b'tochah, hakol tamei": with tumah lodged inside the kaveres, nothing at all escapes.
Working Through the Three Cases
First case: tumah in the gap below the hive. Because the kaveres is elevated a handbreadth, that gap ranks as an ohel, and the tumah travels through it for the hive's full length. Whatever sits upon the hive's surface gains nothing, since a vessel does not serve as a mafsik: it forms no partition able to block tumah from rising through it. And because the tumah has run the whole extent of that lower space, part of which lies within the house, the house is rendered tamei as well.
Second case: tumah lying within the house. A house is itself an ohel, so the tumah occupies all of it, including the gap beneath the section of hive that juts inside. Having gotten in there, the tumah spreads along the hive's whole underside; and the hive affords no shelter to what lies above it, since a vessel does not function as a mafsik against tumah. Consequently what is beneath it and what is above it are alike tamei.
Third case: tumah resting upon the hive. Once again the handbreadth of clearance means the tumah spreads over the hive's full extent. From that it follows at once that the entire space below is tamei, and by way of that space the tumah penetrates the house, so that any keli standing in the house is tamei too.
In each of those three situations one thing at least is rescued: the hive's contents, for a vessel does shield whatever it holds. But where the tumah itself is lodged within the hive, there is nothing further left for it to guard, and tumah takes hold of everything.
Comparing With the Case of a Beehive Lower Than a Tefach
It is worth setting our mishnah side by side with the case of a beehive that is not raised a tefach, since the contrast is what our mishnah is built on.
- Tumah below. With less than a handbreadth of clearance, the tumah rises in a straight column alone, affecting only the point of the hive immediately overhead. The hive's contents stay clean, and the house is plainly unaffected. With a handbreadth of clearance, the tumah fills the whole gap, so all that rests on the hive and everything in the house become tamei, and only what the kaveres holds within is spared.
- Tumah in the house. With the hive resting low, the tumah is confined to the house itself. The vessel shields its own contents, and nothing beyond the house's walls contracts tumah, since the hive's opening is turned toward the street rather than inward. The two openings that do face inward are plugged with straw, and that plugging suffices to bar the tumah from passing through. Once the hive stands a handbreadth high, the tumah filling the house reaches the gap beneath the hive, and since that gap has the necessary height the tumah runs from end to end of it. The whole of that area is tamei; the hive cannot guard what lies on top of it, so everything under it and over it is tamei, its interior alone excluded.
- Tumah above. A low-lying hive transmits the tumah downward in a straight line only, to whatever happens to stand immediately beneath it. Lifted a handbreadth, the tumah covers the hive's whole span, so all that stands underneath is tamei regardless of whether it lies directly below the tumah, and the house contracts tumah too, since that tamei space carries on inside.
- Tumah within the hive. Here the elevation is of no consequence at all. In our mishnah the outcome is self-evident. Yet even with a hive lacking a handbreadth of clearance the halachah is identical: tumah lodged inside fills the whole kaveres and issues out through the pair of holes that open into the house. The hive's mouth may face the street, but those two inner holes look into the house, and although straw blocks them, straw keeps tumah from coming in, not from going out. Either way, then, tumah within the kaveres renders everything tamei.
The principle that carries the entire mishnah is the tefach. Give the space beneath the beehive a handbreadth of height and it becomes an ohel, and from that moment the tumah no longer travels in a narrow column but fills the length of the kaveres and reaches wherever that space reaches.