Keilim, Chapter 16, Mishnah 5. Two rules that the earlier mishnayot laid down are now brought together in one place. Rule one: a vessel of wood or of leather falls under the rules of tum'ah only if a person can pick it up and carry it, and not just when it stands empty. It has to be portable with its load inside. If a container is so oversized that filling it and then lifting it would tear it apart, tum'ah never touches it. Rule two: an object counts as a keli only if it was made to serve over the long run. Whatever was fashioned for a single use and then to be thrown out never enters the category of a keli at all. Our mishnah takes these two measures and applies them to a row of woven baskets.
The Mishnah begins: "Petilya teme'ah". A petilya is a small basket woven from willow twigs in which dried figs are kept, and it can become tamei. Both conditions are satisfied here. The basket really does hold its contents, it can be raised and moved while packed without coming undone, and its owner will go on using it season after season.
"Vachasina tehorah". The chasina, on the other hand, remains tahor. This is an enormous basket woven out of thorn branches in which clay is carried. Nobody doubts that it is a receptacle, yet tum'ah has no grip on it, for the moment it is full it cannot be shifted from its place without falling apart. Whatever collapses under its own contents when a person tries to carry it is not a keli for this purpose.
"Sagnayot shel alin tehorot". Here the mishnah moves to the second rule. Sagnayot are little bowl-like baskets laid over produce such as figs and grapes to shield them. Made out of leaves, they stay tahor, because a covering of that kind was never intended to survive. It does its job for the moment and is then thrown away, and an object not designed to last is no keli.
"Shel netzarim teme'ot". Take those very same bowl-like covers and weave them out of palm fibers, and now they can contract tum'ah. Fibers of this sort hold up, and their owner will reach for the same covers to shield his fruit year after year. Because they are built for durability, they are genuine keilim, and impurity attaches to them.
The mishnah's next case is the "chotal", a small basket plaited from soft palm leaves in which dates are laid away to ripen and from which they are later removed. Of such a basket the mishnah says "shehu noten letocho venotel mitocho, tamei": so long as its owner can insert the dates and afterward draw them back out, it can become tamei, since it is a receptacle that goes on serving him again and again.
But the mishnah continues, "ve'im eino yachol", if he has no way of reaching the dates except by ripping the basket apart or unraveling its weave, then, as the mishnah concludes, "ad sheyikra'enu o ad sheyatirenu, tahor". Such a basket is used once and is wrecked in the very act of emptying it. A disposable wrapping of that sort is never granted the standing of a keli, and tum'ah does not rest on it.
So the mishnah sets out four familiar containers in pairs, each pair demonstrating one of the two requirements. Willow basket beside thorn basket teaches that a keli must be carryable when loaded, while leaf covers beside palm-fiber covers, along with the two kinds of date baskets, teach that a keli must be made to endure.