Terumos Chapter 3, Mishnayos 3 and 4. The previous Mishnah dealt with partners who had not explicitly authorized one another to separate Terumah from their jointly owned produce, and there was a dispute about the case of one of them who separated Terumah on behalf of his fellow without authorization: Rabbi Akiva holds that his Terumah is not valid, while the Sages hold that it is. Rabbi Yosei completes the words of the Sages and adds a qualification: provided that he separates the amount fixed by the Sages, one in fifty.
"Bameh Devarim Amurim":
Our Mishnah continues: "Bameh devarim amurim" - to what does this refer? According to the Bartenura, it refers to the opinion of Rabbi Akiva, who holds that a person cannot effectively separate Terumah from the produce of his partner. According to other versions of the text, one can explain that it refers to Rabbi Yosei as well, who qualified that it takes effect only when one separated the average measure, one in fifty. And to what case does this apply? "B'shelo dibeir" - the assumption is that the one never spoke with his fellow at all, meaning that there was no explicit authorization here and also no refusal to authorize.
Explicit Authorization:
"Aval hirshah es ben beiso o es avdo o es shifchaso litrom - terumaso terumah" - if a person authorized one of his household members (a child over the age of thirteen), his slave or his maidservant, and all the more so his partner, to separate Terumah, the Terumah takes effect. At first glance there is nothing new here, since we already learned in the first Mishnah of the first chapter that a person may authorize others to act on his behalf, so it seems the Mishnah has simply repeated the same law.
Two directions are offered in explaining the novelty here:
The precision in the word "hirshah": "Hirshah" does not mean appointing, but merely permitting. This is not a case of a person who told his son or his partner, "Go and separate Terumah for me," but rather one who said, "I hereby permit you - if you wish, go and do it." A permission of this sort is enough for the authorization to take effect.
The precision in "his slave and his maidservant": In the first Mishnah of the first chapter, five categories of people were listed whose Terumah is not valid even after the fact, and the fifth of them is the non-Jew, derived from the verse that speaks of Bnei Yisrael - who are the ones who give Terumah for the Mishkan. Here we learn about a slave and a maidservant, meaning a Canaanite slave and a Canaanite maidservant, who were not born Jewish and became the slaves of a Jew. Part of becoming slaves is a process resembling conversion: the male is circumcised, and both the male and the female immerse in a mikvah and accept upon themselves the mitzvos that a Jewish woman is obligated in - keeping kosher, Shabbos and the like. They are like half Jews and are not full Jews; a slave, for example, is not counted toward a minyan.
Yet the only thing standing between them and full Jewish status is emancipation: from the moment they are granted their freedom, they automatically become Jews. For this reason the Mishnah teaches us that the slave and the maidservant are "Jewish enough," for lack of a better term, and are not excluded from the possibility of separating Terumah on behalf of their master.
Canceling the Authorization:
The Mishnah moves on to a new topic: the force of the authorization itself. Reuven said to Shimon: I hereby authorize you to be my agent to separate Terumah for me. What is the law if, after Shimon set out on his way, Reuven changed his mind?
"Bitel - im ad shelo taram, ein terumaso terumah" - if Reuven changed his mind and expressed his retraction of the authorization, even though Shimon is no longer standing before him, and Reuven says only to himself that he is retracting and no longer wants Shimon to be authorized, that is enough to remove the authorization. If Shimon then goes and separates Terumah, his Terumah is not valid at all.
"V'im mishetaram - terumaso terumah" - but if the Terumah has already been separated, it is too late. Even though the cancellation is accomplished, according to Rabbi Yochanan, through speech alone, since at the moment Shimon separated the Terumah he was authorized to do so, there is no retracting after the fact, and what is done is done. We learn from this that authorization through speech is sufficient, and likewise its cancellation through speech is effective.
Workers:
The third section of the Mishnah deals with laborers, the hired workers who work for the homeowner. Regarding partners we learned, at least according to the opinion that was accepted as halachah, that a partner is presumed to be authorized - and certainly after the fact - to separate on behalf of his fellow. A laborer is not like that: someone hires a worker to thresh in his granary, and the worker says, "I will do him a favor and separate the tithes for him too, and save him time and trouble" - "Hapoalim ein lahem reshus litrom" - the laborers have no permission to separate Terumah. A laborer has no automatic authorization to separate Terumah in the homeowner's name, and if he did separate, his separation does not take effect.
The treaders - an exception:
There is one exception: those hired to tread grapes in order to produce juice for wine. The Bartenura explains the Mishnah as speaking of a case where the owner of the vineyard is an am ha'aretz, who is not formally obligated to maintain purity at all times. Since he is not obligated to be pure at all times like a chaver, there is a process he would have to undergo, and as we already discussed to some extent in Maseches Demai, one who does not fulfill these conditions has the status of one who is tamei. And not merely out of doubt: the halachah establishes him with the presumed status of tumah, and whatever he touches is considered tamei.
The am ha'aretz thus finds himself in a dead end: he has no way to separate Terumah, since anything he touches of the wine will become tamei, and inevitably he will taste the wine sooner or later and ruin and contaminate everything. For this reason, when he hires chaverim - who are meticulous about maintaining purity - to tread the grapes with their feet, it is self-evident that they were chosen for the job because they are able to separate Terumah properly, and this is considered an implied authorization. They, and only they, are permitted to separate Terumah on behalf of their employer without any explicit authorization, in a case where they are chaverim and they were hired by an am ha'aretz.
And what is the reason for this? "Shehen metam'in es hagas miyad" - because they render the winepress tamei immediately. Here we must be precise, because the word "shehen" ("they") is confusing: according to the Bartenura it does not refer to the treaders, but to the employers, the amei ha'aretz who hire the treaders. They render the winepress tamei immediately: once they begin to taste the wine or the juice, they will render tamei the entire pit and barrel into which the juice is collected, since they are permanently tamei by virtue of being amei ha'aretz. For this reason the Sages permitted and assumed that the treaders are automatically authorized - again, in a case where they are chaverim, according to the Bartenura, and the employer who hired them for the treading is an am ha'aretz.
In summary: In this lesson we learned that the dispute in the previous Mishnah applies specifically "when he did not speak," that is, when there was no explicit authorization; but one who authorizes a member of his household, his male slave or his female slave - their Terumah is valid Terumah, and the Mishnah's novelty lies in the word "hirshah" (permission rather than appointment) and in the fact that a male or female slave is not included in the category of the disqualified non-Jew. We also learned that authorization given by speech and its cancellation by speech are both effective: if he canceled before the other separated, the Terumah is not valid, but once he separated, the Terumah is valid. And finally, that laborers are not authorized to separate on behalf of the homeowner, except for treaders who are chaverim hired by an am ha'aretz, since their employer renders the winepress tamei immediately.