Keilim, Chapter 26, Mishnah 5. Our Mishnah presents a list of flat leather items and asks about each one whether it is capable of contracting tum'at midras, the tumah transmitted by a zav, a niddah or similar person who sits, leans or lies upon an object.
One rule needs to be stated before we reach the list. Tum'at midras takes hold only on an object that serves, among its uses, to hold up a person's weight, as a chair or a mattress does. Yet bearing a person need not be the item's chief purpose. Even something made and used for a completely different task can still fall under tum'at midras, so long as it was set aside to be sat or reclined upon during the times it is not serving that chief purpose. Each of the items listed here fits one of these two categories: either sitting and lying is what it is essentially for, or that is its accepted secondary use.
The items that are subject to midras
The Mishnah opens: "Eilu orot temei'in midras," these are the leather items that can become tamei with tum'at midras.
- "Or shechishev alav leshati'ach" - a bare hide that its owner earmarked for spreading out and sitting upon, functioning much like a mat.
- "Or hakatzav" - the leather apron of the tanner. He wore it through his labor, and once he broke off from work he would use it as a seat.
- "Or hakatavliya" - a hide spread over the frame of a bed and lashed to the frame with cords, upon which one would sleep.
- "Or hachamar" - the leather cloak of the donkey driver, drawn on over his garments as protection against the rain.
- "Or hakatan" - the apron of the flax worker, worn while he combed out the flax so that stray slivers would not damage what he had on.
- "Or harofei" - the physician's leather sheet. When tending to wounds he would drape it over his knees so that blood would not stain his clothing.
- "Or ha'arisah" - the leather lining of an infant's cradle, put in place so that the baby's waste would not dirty the linens.
- "Or halev shel katan" - a leather guard laid over the chest of a young child, shielding him from the claws and blows of a wild cat.
- "Or hakar" - the leather cover of a pillow.
- "Or hakeset" - the leather cover of a mattress. These two were laid over the pillow and the mattress to keep them from being soiled when people sat down on them.
Of all of these the Mishnah rules that they are subject to tum'at midras. In some of the cases listed, being sat or lain upon is the item's own primary function. In the others, that is not the main purpose at all, yet since people do sit or recline on them at times, they too fall under tum'at midras.
The two aprons in dispute
The Mishnah then raises two more items: "or hasaruk" and "or hasorek." These are two different craftsmen, similar sounding but distinct. The first is the leather apron of a comb maker, the artisan who manufactures combs. The second belongs to the comber, the one who combs out the wool, who would fasten a piece of leather over his lap while working.
"Rabbi Eliezer omer: midras, vaChachamim omrim: temei met." Rabbi Eliezer holds that these two aprons can indeed contract tum'at midras, since on occasion they are used for sitting or lying upon (and of course they are also capable of receiving ordinary tumah, such as the tumah of a corpse). The Chachamim disagree: they can receive only tum'at met, the tumah of a corpse and the like, but not tum'at midras, because they were never intended to be sat or lain upon at all.