Mishnah 10 in chapter 4 of Maseches Terumos continues the same topic as the previous mishnayos, except that here the strict and lenient opinions switch places: Rabbi Eliezer is the lenient one in the way the hundred is counted, and Rabbi Yehoshua is the strict one - unlike the previous mishnah, where Rabbi Eliezer was strict and Rabbi Yehoshua lenient. That is why the mishnah opens with the word "uvazu" ("and in this case"), meaning: in this case Rabbi Eliezer is lenient.
The case:
A person has ten jars in which he stores his pressed figs, and each jar holds twenty litras of figs - two hundred litras in all. He knows that into the mouth of one of the jars he pressed one litra of Terumah figs, in the very top layer, and it is still lying there. Afterwards, however, his children shuffled the jars around in the storeroom, and there is no longer any way to know which of the ten jars is the one with the Terumah figs packed in its mouth.
Two ways of looking at the mixture:
Looking at the entire quantity: Before us are ten jars containing two hundred litras of figs, of which one litra is Terumah and one hundred ninety-nine are chullin. That is one in a hundred ninety-nine, and the mixture is entirely permitted.
Looking at the location of the prohibition: There is no doubt at all regarding the bottom nineteen litras in each of the jars, since the Terumah lies only in the top layer. It emerges that the doubt extends only over the ten top layers: nine layers of permitted figs and one layer of Terumah - one out of ten, which is not enough to nullify.
Rabbi Eliezer is lenient: the location makes no difference, and all the figs may be combined into the mixture, even though we know that the prohibited item is in the upper part of the vessel.
Rabbi Yehoshua is strict: the location does make a difference, and the bottom nineteen litras in each jar may not be combined. Only the ten top layers remain, and they are not enough.
It is worth noting that it is not clear - neither to us nor to the commentators - why Rabbi Yehoshua should be strict specifically regarding location and lenient regarding color and shape. There is no necessarily satisfying analytical answer to this distinction, or at the very least the matter is not clear; this is also what emerges from the sources that were examined. In any event, we will accept the matter as given.
The language of the mishnah: "HaDoreis litra ketzios al pi hakad v'ein yadua eizo hi".
"HaDoreis" - a term of treading, and here in the sense of pressing inward. From this too, in modern usage, a bird of prey is called a 'doreis', on account of the way it seizes with its talons.
"Litra" - a Roman unit of weight from the times of the Mishnah, roughly the weight of a pound. From this comes the abbreviation for pound (lb), which originates in the Latin word libra, meaning scales, weight or pound, as well as the name of the constellation Libra.
"Ketzios" - dried figs. The name derives from the implement called a 'ketziah', a sort of knife that cuts off the stems of the figs.
"Al pi hakad" - specifically in the top layer at the mouth of the jar.
"V'ein yadua eizo hi" - it is not known in which of the jars that litra is lying, whether because he forgot or because the jars got shuffled.
"Rabbi Eliezer omer: ro'in osan k'ilu hen perudos" - one should view all two hundred litras as though they were separated and mixed together with one another, and not as lying only in the top layer of the vessels. The word 'perudos' is like the expression in the Megillah about the Jewish people, "mefuzar umeforad" (scattered and dispersed). Consequently, "v'hatachtonos ma'alos es ha'elyonos" - the bottom layers join the count of a hundred (in fact a hundred ninety-nine) and nullify the top layer, that litra of Terumah figs.
Rabbi Yehoshua omer: "Lo" - since it is known that the Terumah is located in the top layer, one may not view them as separated and mixed together, and only the top layers of each of the jars may be combined. And since in each jar the top layer contains only one litra, nullification would take effect only if he had a hundred and one jars: a hundred permitted top layers against one prohibited one. In our example, all ten top layers are forbidden as a medumah mixture.
In practice, the bottom layers in each of the ten vessels, which are clearly not Terumah, may be eaten. But whatever is subject to doubt - the top layer of each of the vessels, in which the Terumah may be lying - must be removed and sold to a kohen at the price of the total quantity, minus that one litra which is Terumah in any case and for which he is not paid.
The halachah: The halachah follows Rabbi Yehoshua, as it generally does, and so it is in this mishnah as well - even though it is not entirely clear what the underlying analytical principle is that distinguishes between location, which does make a difference as in our mishnah, and shape and color in the previous mishnah, which make no difference with regard to reaching the hundred needed to permit the mixture.