Taharos, Chapter 7, Mishnah 7. Throughout this chapter the Mishnah moves from case to case involving the am ha'aretz, a Jew who is lax about tumah and taharah, and in each one it weighs a single question: are we obligated to suspect that he touched our belongings, or may we take it for granted that he stayed away from them? The present mishnah puts that question to a person who deposits his garments with someone else and later comes back for them.
Clothes left with the bathhouse attendant
"Hamani'ach es kelav bechalon shel odiyarin": one who leaves his clothes in the window of the odiyarin. Odiyarin is one more of the Greek words that the Mishnah is fond of, and it refers to the bathhouse attendant. His window served as what we would call a locker. A person on his way into the bathhouse hands over his clothes and they are stored there until he comes back out.
"Rabbi Elazar ben Azaryah metaher": Rabbi Elazar ben Azaryah rules that the clothes are tahor. We do not presume that anyone went through them. The reasoning continues the theme of the preceding mishnayos, which assumed that a thief is too frightened to roam. Here too, if the clothes are still sitting where they were left, that itself proves that nobody was prepared to lay a hand on them, since a person who is afraid of being taken for a thief keeps his hands off entirely rather than poking around in another man's bundle.
"Vachachamim omerim: ad sheyiten lo es hamafte'ach o chosam, o ad sheya'aseh siman": the chachamim disagree. In their view the clothes are not presumed tahor unless the owner received the key to the locker, or a seal, or unless he made some identifying mark, for example folding the garments in a particular way or arranging them so that he would notice at once if they had been disturbed. As long as none of these three safeguards was in place, the clothes must be treated as tamei.
Clothes left from one vintage to the next
"Hamani'ach es kelav migas zo legas haba'ah": one who leaves his garments with another person from the current season of pressing grapes until the season of pressing that will come the following year, an entire year in which they sit in that person's possession. "Kelav tehorin": the garments retain their taharah. "UveYisrael, ad sheyomar: belibi hayah leshomram": but where a Yisrael held them, only if he states that he intended all along to watch over them.
These lines are worded ambiguously, and there are two ways to understand who is being spoken about in each half. Both readings have their strengths.
The Bartenura reads the first ruling, "kelav tehorin," as describing garments deposited with a non-Jew. A non-Jew hesitates to handle a Jew's property, since to his eyes these are people with an odd and intricate system of rules that he would rather not get tangled up in, and so we take for granted that he never touched the clothing. The closing clause then turns to a Jew who is an am ha'aretz, and being a Jew is exactly why no such hesitation restrains him. He assumes he is perfectly familiar with the subject of tumah and taharah, having studied it as a child, and he handles whatever he likes. His deposit therefore carries no presumption of taharah unless he says explicitly that he was actively guarding the garments, that safeguarding them was his conscious intention. Even a decent and sincere person does not help us here, because without his having kept in mind the whole time that these garments must not be made tamei, being trustworthy by nature does not suffice.
A second approach understands "kelav tehorin" as speaking not of a non-Jew at all, but of garments belonging to a kohen, set opposite the Yisrael named in the next clause. On this reading, an am ha'aretz is not suspected of tampering with what belongs to a kohen. Just as a non-Jew shies away from a Jew's food by instinct, the am ha'aretz sees a kohen's clothing and recalls the lesson of his childhood home, that a kohen's possessions are not to be disturbed, and he keeps his distance. But when the garments belong to an ordinary Yisrael, the am ha'aretz feels entirely comfortable with them, and we presume he did handle them, unless he says, "Belibi hayah leshomram," that guarding them was what he had in mind.
So the mishnah leaves us with two respectable ways of reading its closing case, and with one consistent lesson running through the whole discussion: things left in another person's hands stay tahor only when there is a real reason to believe that the other person kept his hands off them, whether that reason is a key, a seal, a recognizable sign, natural reluctance, or an explicit statement that he was watching over them the whole time.