Ohalos, Chapter 14, Mishnah 3. This chapter is occupied with a projection or covering positioned by the entrance of a house, and with the question of when such a covering joins itself to the doorway so that tumah resting beneath it is drawn inside. Our mishnah takes up an unusual case: not a ledge built out from the wall, but a plain rod resting above the entrance.
The mishnah opens with its case: "Kaneh she'al gabei hapessach", a rod lying over an entranceway. Imagine a homeowner walking up to his front door and spotting a pole stretched across above it. And how high may that pole sit and still be relevant? The Mishnah's words are "afilu gavoha me'ah amah": its elevation may reach a hundred amos.
It pays to feel how enormous that measurement is. A hundred amos is roughly two hundred feet. Consider that the distance from the floor of a room to its ceiling is generally somewhere between eight and ten feet. Even taking the generous figure of ten, two hundred feet is about twenty stories of height. That is where this rod is sitting, high above the entrance of the house.
And still the mishnah rules: "meivi es hatumah kol shehu", it brings in the tumah, whatever its size. If a piece of a meis lies beneath the rod, the rod functions as an ohel, and the tumah is conveyed into the house. Nor does the mishnah require any minimum thickness for the rod itself; even a rod that does not measure a square tefach does the job.
Why a Rod Is Treated More Strictly Than a Ledge
The Bartenura raises the obvious difficulty. In the preceding mishnah we were taught about a ziz, a projection or overhang extending from the wall above the entrance, and there the halachah was that it draws tumah into the house only when it is within twelve tefachim of the doorway. (A tefach is approximately the width of a clenched fist.) Once the ziz stands higher than twelve tefachim, it is no longer regarded as joined to the doorway at all. How, then, can our mishnah declare that a mere rod conveys tumah even from a hundred amos overhead?
The Bartenura answers: "bakaneh hichmiru mishum demitaltel", with a rod the Chachamim were stringent precisely because it is portable. A ziz is fixed into the wall and is going nowhere. A rod is another matter entirely.
The Sidrei Tahara sketches the arrangement for us. Nothing binds this rod to the wall at all. What the householder did was insert a pair of nails or stakes and rest the pole across them. Taking it down and putting it back costs him no labor whatsoever. True, at such an altitude he would need an open window or a ladder in order to reach it, yet the rod remains something he can remove whenever he pleases, while the ziz of the previous mishnah belongs to the masonry itself.
Why should portability make a halachic difference? The Eliyahu Rabbah, printed alongside the text in the standard editions of Mishnayos, supplies the reasoning. Since nothing stops the owner from relocating the pole, he may well come along one day and reposition it so that it rests immediately over the entrance. Where it happens to be lodged today therefore tells us nothing about where it will be found tomorrow. And in that lower position it would count as an extension of the doorway, with any tumah underneath it certainly reaching inside. Because that outcome is always within reach, the Chachamim ruled strictly already now, while the rod is still far overhead.
Rebbi Yochanan ben Nuri's Objection
Everything until now is "divrei Rebbi Yehoshua", the position of Rebbi Yehoshua. A second Tanna disputes it. Rebbi Yochanan ben Nuri maintains that a rod warrants no greater severity than a ziz; in his words, "al yachmir", let no added strictness be applied, "zeh min haziz", in this instance as against the case of a ziz. For him the boundary of twelve tefachim governs both alike: once the pole is farther than that from the entrance, it carries nothing indoors. Tumah resting beneath it stays exactly where it is, outside the house.