Keilim, Chapter 2, Mishnah 7. Earlier in this chapter the Mishnah listed flat earthenware items that cannot receive tumah at all, because an earthenware keli becomes tamei only through its inner space, and a flat surface has no inner space to speak of. Our mishnah now presents a parallel list, item by item quite similar to that earlier one, with one decisive difference: every item here does have some sort of receptacle, some place that holds its contents, and therefore every item here is susceptible to tumah.
The Mishnah introduces the list: "hatemei'in shebiklei cheres," these are the ones among earthenware vessels that do become tamei.
A tray with a rim and a coal shovel
First, "tavla sheyesh ba lizbez," a serving tray that has a raised edge running around it. That edge is not decoration; it does real work, keeping the dishes placed on the tray from sliding off. Because it encloses a space, the tray counts as a receptacle and can become tamei.
Next, "umachta sheleimah," a coal shovel that is intact. This shovel is raised on all four sides, so that the coals it carries stay in place rather than spilling out. Once again there is a genuine enclosure, and once again the keli is susceptible.
A tray filled with attached bowls
"Vetavla shehi meleiah ke'arot." The Mishnah now turns to a tray that is filled with bowls. This is not a tray on which loose bowls have been set down. It is a single piece of earthenware formed with compartments, with the bowls themselves part of the original vessel and physically joined to it. The Rambam notes that such vessels were common in Egypt in his day.
The ruling: "nitmeyat achat meihen besheretz" - should a sheretz, one of the eight creeping creatures whose carcass conveys tumah, drop into the hollow of one particular bowl, that bowl alone contracts tumah, "lo nitme'u kulam", and its neighbors remain tahor. Their being joined to the tray and to each other changes nothing, because every bowl is put to use by itself and is therefore reckoned a vessel unto itself. What befalls one leaves the standing of the rest untouched.
Now the opposite result. "Im yesh lah lizbez odef": where the tray is ringed by an outer edge that stands taller than the sides of the bowls themselves, then "nitmeyat achat meihen, nitme'u kulan", one bowl made tamei by a sheretz brings tumah upon all of them. Everything turns on the order in which things happen. The sheretz cannot reach the hollow of any single bowl without first entering the space enclosed by that raised outer edge. In that instant the tray itself has become tamei, and the bowls, which form part of that same tray, are swept along with it as portions of one vessel that has already contracted tumah.
The spice box and the scribe's case
"Vechen, beit tavlin shel cheres": the identical halachah governs a clay container for spices that is partitioned into distinct sections, each spice in its own place. So too "vekalamarin hamitu'amot", a scribe's case built in pairs or sets of compartments, rather like a desk organizer, where he stores what his craft requires: ink in one section, writing implements in another.
The law here follows precisely the pattern of the compartmented tray. Should a sheretz drop into the hollow of one section, tumah is confined to that section alone, since every division counts as a vessel in its own right. But where the box is bounded by a rim or wall standing taller than the partitions within it, the sheretz on its way down first passes through that upper enclosed space, and the box in its entirety, every compartment included, becomes tamei.
A wooden spice box and tamei liquid
So far the subject has been clay. The Mishnah now moves to a spice box made of wood, in order to mark both where the two materials agree and where they diverge. In this new case the agent of tumah is not a sheretz but a liquid that is itself tamei. Such a liquid, as we have learned, conveys tumah to a keli by rabbinic enactment alone, and that rabbinic tumah carries a further feature: where the liquid meets nothing but a vessel's exterior, the exterior alone turns tamei and the interior keeps its taharah. That principle is now brought to bear on a partitioned wooden spice box.
"Uveit tavlin shel eitz", and regarding a wooden spice box, "shenitma echad bemasheh, lo nitma chaveiro". Tamei liquid reaching the inside of one section renders that section tamei, while the section beside it, the two of them having a divider in common, remains tahor. Consider what such a divider actually is: a single board serves at one and the same time as the inner face of one section and the outer face of the next. The liquid that landed in the first section met a surface that was interior there and exterior for its neighbor. And since tamei liquid reaching a vessel's exterior renders nothing beyond the exterior tamei, the inside of the second section stays tahor.
How much of the shared wall is tamei?
It emerges from this ruling that although the second compartment itself remains tahor, the dividing wall between the two has contracted tumah. The Mishnah now asks how much of that wall is affected.
"Rebbi Yochanan ben Nuri omer": his position is that the thickness of the board is itself split, "cholkin et ovyo". Of its two halves, "hameshamesh latamei, tamei", the portion facing the section that turned tamei is tamei; and as for the other, "hameshamesh latahor, tahor", the portion serving the section that stayed clean keeps its taharah. He is ready to draw a line down the middle of a single board only because the entire tumah under discussion, the tumah of liquids, carries no more than rabbinic weight.
The Chachamim disagree. In their view, even on this rabbinic level the wall in its entirety becomes tamei, and their position is the one that stands.
When the outer rim rises above the dividers
Everything discussed so far assumed a spice box whose internal dividers reach the same height as its outer walls. The Mishnah closes by teaching the case where the dividers fall short of the outer wall.
"Im yesh lo lizbez odef": where the box is ringed by an edge that stands taller than the partitions separating one section from the next, then "nitma echad meihen", once tamei liquid has rendered a single section tamei, "nitma chaveiro", the sections beside it turn tamei together with it. That projecting edge binds everything beneath it into one vessel, and tumah in any portion of a single vessel is tumah throughout it. The inner divisions have lost all significance here: the edge has gathered them into one keli, so that tumah in a single section reaches every one of them.