Uktzin, Chapter 1, Mishnah 1. This masechta takes up where the earlier masechtos of tumah and taharah leave off, dealing with food that has contracted tumah and with its power to pass that tumah along to other foods and other objects. What our masechta comes to define is the outer question: which parts of a food item count as the food itself for these purposes, and which parts do not.
Picture an apple with a stem protruding from it. That little piece of wood, which once joined the fruit to the tree, is what our masechta calls the ukitz, and the whole tractate is named for it. The question is whether that stem is treated as part of the fruit, so that touching it is as though one touched the fruit itself. The practical consequence is clear: if something tamei came into contact with the stem, would the fruit itself become tamei through that contact?
Before entering the Mishnah, it is worth setting out four basic rules that govern food and tumah:
- It has to be meyuchad lema'achal adam, set aside as human food. An item that people do not normally eat does not enter these halachos on its own; a person has to actively designate it for eating, even if he himself is prepared to eat it as is.
- It has to be muchshar lekabelas tumah, made susceptible to tumah. Susceptibility comes about when the food is wet by one of seven liquids: dew, wine, oil, blood, milk, the honey of bees, and water.
- Produce still mechubar lekarka, joined to the soil in which it grows, is immune to tumah entirely for as long as it remains attached.
- Once hechsher lekabelas tumah has taken place, even the tiniest quantity of food can itself become tamei. Passing tumah along to something else, however, demands a shiur: the food must hold the volume of an egg, a kabeitzah.
With that in hand, the Mishnah opens: "Kol shehu yad velo shomer, mitamei umitamei velo mitztaref." A yad is a part of the food that a person does not eat, yet which serves as a handle, a place to grip the food while eating it. In the times of the Mishnah, figs and dates were eaten in just this fashion: one held the stem and chewed the flesh off it. Such a protrusion is a yad. The Mishnah adds that we are speaking here of something that is velo shomer, that does not guard the fruit. That is, were it torn away, the fruit's freshness and shelf life would not be affected at all.
Of such a handle the Mishnah teaches two directions of law. Mitamei: if the fruit becomes tamei, the attached handle becomes tamei along with it. Umitamei: and in the other direction, if something tamei touches the handle, the fruit itself becomes tamei through it. In both directions, the handle is treated as bound up with the fruit.
But there is a limit: velo mitztaref, it does not join together with the fruit to make up the required measure. Since a food needs a kabeitzah in order to transmit tumah onward, if the fruit reaches a kabeitzah only when the stem is counted in, the stem does not complete the shiur, and the fruit cannot transmit tumah.
The Mishnah now moves to the shomer, the portion whose function is to protect the produce, a fruit's skin being the standard case: "Shomer af al pi she'eino yad, mitamei umitamei umitztaref." Although such a covering gives a person nothing to grip, it shares the fruit's status in both directions: tumah that reaches the fruit spreads into the skin, and tumah touching nothing more than the skin renders what is inside it tamei too. Here, though, a third word is added: umitztaref. Since a shomer has the standing of genuine food, the covering is measured together with what it wraps, and if the two of them together come to a kabeitzah, the fruit is able to pass tumah on to whatever it touches.
Finally, the Mishnah addresses a part that is neither: "Lo shomer velo yad, lo mitamei velo mitamei." Something attached to the food that neither protects it nor serves to hold it is simply not reckoned with the food at all. It does not become tamei when the food becomes tamei, and it does not convey tumah to the food if it itself becomes tamei. And if it does not even enter into those laws, it certainly does not combine with the food to make up the kabeitzah needed to transmit tumah.
Three categories, then, emerge from this opening Mishnah: a yad, which is bound to the food for tumah in both directions but does not add to its measure; a shomer, which is treated as the food itself in every respect; and a part that is neither, which stands entirely outside the food's laws of tumah.