Uktzin, Chapter 3, Mishnah 2. This chapter is built around one central question: what does a food have to undergo before it can be mekabel tumah? Two separate conditions can stand in the way. The first is hechsher: as we have learned earlier, ordinary food does not become susceptible to tumah until it has first come into contact with one of the seven mashkim, the seven liquids that are machshir. The familiar siman for them is Yad Shachadam: yayin (wine), devash (honey), shemen (oil), chalav (milk), tal (dew), dam (blood) and mayim (water). The second condition is machshava: an intention that designates the item as food. Something that people do not ordinarily eat is not automatically considered ochel, and until a person mentally sets it aside for eating it stands outside the category of food altogether.
Because there are two conditions, there are four possible combinations, and the Mishnayos of this chapter sort various items among them. Some items require hechsher but not machshava, because they are naturally human food and need no designation. Some require machshava but not hechsher. Some require neither. And some, the subject of our Mishnah, require both: first a person must decide that this is food, and only then can contact with a liquid render it susceptible to tumah.
The list of items
The Mishnah begins with the case of "Hachotech min ha'adam, umin habeheima, umin hachaya, umin ha'ofos" - a person who slices off a portion of meat, whether from a living human being, from a beheima (a domesticated animal), from a chaya (a wild animal), or from fowl.
Regarding a piece cut from a living human being, the halachah is that tumah attaches only when a complete eiver, a full limb, is severed. Flesh alone, cut from a living person, is not mekabel tumah on account of its own status. If it is going to be tamei at all, it will have to be as food, and since flesh of this sort is not something people eat, it first needs machshava.
The Mishnah continues: "min nivlas ha'of hatamei" - from the carcass of a non-kosher bird. Such a carcass does not carry the halachah of a neveila that is metamei on its own. Here too, then, the only path to tumah is the path of food, which means machshava is required.
"V'hachelev bikfarim" - and the fat of an animal, in the villages. The Mishnah is precise about the location. In the villages this fat is not normally eaten, so it needs a designation as food. In the large cities, where all kinds of people are found and one does encounter those who eat it, it would already be regarded as ochel.
"V'shaar kol yirkos sadeh" - every other kind of wild growth of the field, the sort of vegetation that is not part of the normal human diet, "chutz mishmarkoyim ufetriyos", with truffles and mushrooms left out of the rule. They too come up on their own, and still no designation is called for, since people genuinely do eat them.
The additions of the Tannaim
Several Tannaim add further exceptions, items which in their view are eaten naturally enough that no designation is needed.
- Rebbi Yehuda rules "chutz mikrishei sadeh v'hargila v'neitz hachalav", removing from the list wild leeks of the field, purslane, and neitz hachalav, a plant so named because its sap runs white like milk.
- Rebbi Shimon holds "chutz min ha'akaviyos", leaving out the cardoon.
- Rebbi Yosi holds "chutz min haklusin", leaving out klusin, which are acorns.
The conclusion
The Mishnah closes: "Harei eilu tzrichin machshava v'hechsher" - all of these, apart from the exceptions just listed, require both machshava and hechsher. Machshava, because these items are not ordinarily consumed and must therefore be designated as food before they can enter the category of ochel at all; and hechsher, because even once they are food, they cannot be mekabel tumah until they have had contact with water or with one of the other liquids that are machshir.