Keilim, Chapter 16, Mishnah 1. One idea has stood beneath this entire masechet: tumah attaches itself only to something that qualifies as a keli, an article that genuinely serves a person. From that single idea flow two practical results, and both of them appear in this mishnah. On one side, once an article has broken and can no longer perform the task for which it was made, its status as a keli has lapsed, and tumah has nothing to grip. On the other side, an item still in the hands of the craftsman, not yet usable, has not yet acquired that status to begin with. Our mishnah starts with the broken article and finishes with the one still being made.
A wooden article that comes apart in two
The opening ruling is "Kol keli etz shenechlak lishnayim tahor": every utensil made of wood that has been divided into two parts is pure. Should it have carried tumah until then, the moment of the break terminates that tumah, for the remnants are no longer a serviceable article. The reverse follows as well: an unaffected utensil that comes apart can no longer be rendered tamei afterward, since nothing before us answers to the definition of a keli.
Three cases outside the rule
The mishnah immediately names cases that do not follow this rule: "Chutz mishulchan hakaful vetamchuy hamiznon veha'ipifiron shel ba'al habayit." One is a table that folds, constructed from two panels fastened to one another. Another is a serving tray partitioned into several sections, with a separate food placed in each. The third is the wooden seat found in a private home, likewise put together from distinct parts.
The common thread is that either portion functions independently. Half the folding table remains serviceable; a fragment of the partitioned tray still holds food; a section of the seat still supports a person. No half depends on its counterpart in order to be useful, and so each half carries the identity of a keli by itself. Consequently, when one of these three had been tamei and then divided in two, the tumah remains with both parts. The converse is equally true: a clean utensil of this kind that separates is still susceptible afterward, because neither portion ever forfeited its standing as a utensil.
Rabbi Yehudah's additions
"Rabbi Yehudah omer, af hamagis vehakad haBavli kayotzei bahen." Rabbi Yehudah broadens the list with the magis and with the Babylonian kad, holding that the identical halachah governs them. Should such an article separate into two, the tumah stays with each portion, since every portion counts as a complete keli in its own right; and for precisely the same reason, each portion remains capable of becoming tamei even after the separation.
From what point is a wooden utensil susceptible?
The mishnah now takes up the opposite question: during production, when does an object cross the threshold and become a keli that tumah can reach? The illustration is a bed. In that era such a bed was a four-sided wooden frame, with cords drawn tightly from one side to the other; the network of cords served as the surface on which a person, or a mattress laid over them, would rest. The frame itself was then rubbed down with the coarse hide of a fish, which functioned as sandpaper, and finally given a polish.
"Klei etz me'eimatai mekablin tumah? Hamitah veha'arisah mishe'yeshufem be'or hadag." Susceptibility begins for the cradle and for the bed as soon as the craftsman has rubbed them with the fish hide and removed the splinters. Once that rubbing is done, a person can comfortably make use of them, and at that instant they are keilim capable of receiving tumah, notwithstanding that the polishing stage still lies ahead.
"Gamar shelo lashuf, temei'ah." Suppose the craftsman resolves that he will not smooth the wood whatsoever, and expects to sleep on it or lay a child in it precisely as it stands, coarse surface and splinters and all. Even then it is susceptible to tumah. His resolution brings the labor to an end, and what remains before him is an article ready for service.
"Rabbi Meir omer, hamitah mishe'yesareg bah shelosha batim." Rabbi Meir sets the moment earlier: once three courses of cord have been drawn across the breadth of the frame, the bed is already susceptible, even though the stringing is incomplete and the wood has not been touched by the fish hide at all.
The mishnah has therefore marked both ends of a utensil's existence. Its life opens the moment it is capable of doing what it was intended to do, whether that point is fixed by the rubbing of the wood, by the maker's decision to leave it unrefined, or by the first courses of cord. Its life closes when it breaks and can serve no longer, except where the separated parts remain serviceable, and then each part carries on as a utensil of its own.