meta: {"file": "/data/tomer/Sefaria-Export/txt_done/Modern Works/English Explanation of Mishnah/Seder Tahorot/English Explanation of Mishnah Zavim/English/merged.txt"}
text: English Explanation of Mishnah Zavim
  ביאור אנגלי על משנה זבים
  merged
  
  This file contains merged sections from the following text versions:
  -Mishnah Yomit by Dr. Joshua Kulp
  -
  
  English Explanation of Mishnah Zavim
  
  Introduction
  
  A "zav" is a man who had a non-seminal genital discharge, assumedly do to some illness. When a man has two such discharges, he must count seven days before he can go to the mikveh and become pure, however he is not obligated to bring a sacrifice unless he sees three times in one day or for three days straight.  A zav and a zavah (a woman who had non-menstrual blood), a niddah and a woman who gave birth defile things by contact, by carrying and by shifting. This is true whether the pure person carries or shifts the impure person without contact or vice versa, the impure person carries or shifts the pure person. This is unique to the category of zavim for in other cases of impurity, the impurity is conveyed only if the pure person carries the impure.  The following words will consistently be written in transliteration: 1) Zav—male with non-seminal genital discharge. 2) Zavah—female with non-menstrual blood. 3) Zivah—the discharge itself. 4) Zov—same as zivah. 
  
  
  
  
  
  
  
  
  
  Mishnah 1
  
  If a man has seen one issue of zov: Bet Shammai says: he is to be compared to [a woman] who observes day a for each day. But Bet Hillel says: he is to be compared to one who has had a seminal emission.  The two houses disagree in this mishnah concerning a man who had one emission of discharge of zov (see intro for all terms). According to Bet Shammai his status is like a woman who had an emission of zivah one time. Such a woman must wait a day and if she is pure that day, she will be pure at the end of the day. If she sees zivah for three straight days then she will be a full zavah. So too a man who saw one issue of zov must wait a day to see if he sees another issue. If he does, he is a zav and he will retroactively defile everything he touched, laid upon or sat upon from the time he saw the first issue. One who shifts the zov itself is also defiled. Bet Hillel says that a man who has had one issue of zov has the same status as one who has had a seminal emission. He does not defile things by laying on them or sitting on them and one who shifts the semen is not defiled. If he sees a second time, then he is a zav, but only from that point and onward.
  Should he see [one day] and on the second it stopped, and on the third day he saw two [issues], or one [issue] that was as copious as two: Bet Shammai says: he is a full zav. But Bet Hillel says: he defiles those objects on which he sits or lies, and must also go into running water, but he is exempt from the sacrifice.  As we learned in the introduction, a full zav is one who saw three issues in one day or one issue for three straight days. The two houses here debate concerning a man who saw three issues, but not in one day or in three straight days. According to Bet Shammai this person is considered a full zav, for the first sighting of zov counts with the second two. Not only is he impure and must immerse in living water, but he is also liable to bring a sacrifice. Bet Hillel says that the discharge on the first day does not count together with the discharges that came two days later. Therefore, he is considered as if he had seen discharge only twice. He defiles through lying or sitting and he must immerse in living waters (a live spring, not a mikveh), as must a zav, but he is not liable for a sacrifice.
  Rabbi Elazar ben Yehudah said: Bet Shammai agrees that in such a case he is not real zav.  Rabbi Elazar ben Yehudah disagrees with the version of this dispute contained in section two. According to him since he only saw zov once and then had a day in which he was pure, the sightings on the third day do not join the sighting on the first day.
  What do they disagree about? The case of one who saw two [issues], or one [issue] that was as copious as two [on one day], and stopped on the second day, and on the third day he saw another [issue]. Bet Shammai says: he is a real zav; But Bet Hillel say: he only defiles those objects on which he sits or lies, and must also go into running water, but he is exempt from the sacrifice.  Rabbi Elazar ben Yehudah says that the disagreement is concerning a slightly different situation. He saw zov twice on the first day, or one discharge that counted as twice. Now he is clearly a zav, although he is not yet liable for a sacrifice. If he sees discharge again on the third day, Bet Shammai says that since he is already a zav, this sighting joins with the first two and he is a full zav. Bet Hillel maintains their opinion that unless he sees for three straight days or three times on one day, he is not a full zav.
  
  Mishnah 2
  
  Introduction
  A zav must wait for seven clean days to become pure. Our mishnah deals with a man who during those seven days in which he is supposed to be clean sees a discharge of semen.
  If one sees an issue of semen on the third day of counting his zov: Bet Shammai says: it undoes the two preceding days; But Bet Hillel says: it undoes only that day.  Bet Shammai holds that if he has a seminal discharge on the third day of waiting to become clean from his zov, the first two days of cleanness are undone. He must now start his count over again. Bet Hillel says it only undoes the day on which he experienced the discharge. After that day he may resume his count.
  Rabbi Ishmael says: one who sees it on the second day, it undoes the preceding day.  Rabbi Ishmael says that even Bet Hillel agrees that if one sees a seminal discharge on the second day, it undoes the first day. He must have two days of cleanness for them not to be undone.
  But Rabbi Akiva says: it matters not whether he saw it on the second day or on the third day: Bet Shammai says: it undoes the two preceding days; And Bet Hillel says: it undoes only that day.  Rabbi Akiva disagrees with Rabbi Ishmael and maintains that according to Bet Hillel it doesn't matter whether the seminal discharge occurred on the third or second day; in both cases Bet Hillel holds that it causes only that day not to count.
  But they agree that if he saw it on the fourth day [of counting] it undoes only that day.  The two houses agree that if he counted three full days of cleanness, they are not undone by seeing a seminal discharge. This is because three days is the amount of time it takes one to become a zav in the first place.
  This is if he saw semen; but he saw zov, then even if this had occurred on the seventh day, it undoes all the days that had preceded.  However, this is only true if he had a discharge of semen. The two houses argue whether and when a discharge of semen undoes the clean period for a zav. But if he sees another issue of zov, clearly this undoes the entire clean period and he must start the count all over again.
  
  Mishnah 3
  
  If he saw one issue on one day and two on the next day, or two on one day and one on the next day, or three on three [consecutive] days, or three nights, he is a full zav. This mishnah lays out the bottom line rule with regard to what is required for a person to become a full zav. If he has a three discharges on up to three days or nights straight, no matter what the combo, he is a full zav. He must bring a sacrifice at the end of his period of cleanness. We should note that this is different from a zavah. For a woman to become a zavah she must have non-menstrual blood flow on three consecutive days.  Three times on one day does not make her a zavah.
  
  Mishnah 4
  
  If he saw one [issue] and it stopped long enough for an immersion and a drying, and after that he saw two issues, or one as copious as two;Or if he saw two [issues] or one as copious as two, and it stopped long enough for an immersion and a drying, and after that he again saw an issue, he is a full zav.This mishnah deals with the question of how to determine if one discharge should be divided into two. In other words, how long must there be between discharges for them to count as two?The answer in both of these cases is that if the flow stops long enough for him to have immersed and then dried off, the second flow is considered to be new.
  
  Mishnah 5
  
  If he saw one issue which was as copious as three, lasting as long [as it takes to go] from Gad-Yav to Shiloah, which is the time it would take to bathe and dry twice, he becomes a full zav.  The mishnah now mentions the possibility that a man could have one issue of zov (discharge) and it would be sufficient to count as all three issues necessary to become a full zav. The discharge would have to last long enough to bathe and dry twice, once in between each issue, had they been separate. In addition, the mishnah defines this as the time it would take to walk from a place called Gad Yavan to the Shiloah spring in Jerusalem. Unfortunately, we don't know where "Gad Yavan" is. But assumedly it is near the Shiloah spring, the source of water for the ancient city of Jerusalem.
  If he saw one issue which was as copious as two, he defiles [objects] on which he lies or sits and he must immerse in running water, but he is exempt from bringing a sacrifice.  One issue can count as two to make a man into a zav, but not a full zav. The difference between a full zav and a zav is that a full zav must bring a sacrifice at the end of his period of cleanness.
  Rabbi Yose said: they have not spoken of "one issue as copious" unless there was sufficient to make up three.  Rabbi Yose said that there is no legal consequences to seeing one issue of zov that is as copious as two. Either the issue was as copious as three, in which case he would be a full zav, or it would count as only one. This means that Rabbi Yose would disagree with most of the mishnayot that we have seen so far in this chapter.
  
  Mishnah 6
  
  Introduction
  Our mishnah deals with a man who has an issue at twilight. The question is does the change of day divide one issue into two issues?
  If he saw one issue during the day and another at twilight, or one at twilight and the other the next day: If he knew that part of the issue occurred at day-time and part the next day, he is certain with regard to a sacrifice and uncleanness. But if it is in doubt whether part [of the issue] occurred at day-time and part on the next day he is certain with regard to uncleanness, but in one of doubt in with regard a sacrifice.  In this case a person had an issue of zov during the day and then another at twilight, a time which is not easy to determine as either night or day. Or he had an issue at twilight and then another the following day. We need to determine whether the issue he had at twilight counts as two issues, such that he is now a full zav. Or does it count as only one, such that he is a zav, but not a full zav? If he knew that part of the issue that happened at twilight occurred during one day and part the next, then he would certainly be impure and he would certainly be liable for a sacrifice. We learn here that a new day causes one issue to be legally considered two. [We should note that I'm not sure if it's all that possible to know whether it occurred during one day or the next day. The mishnah wants to teach the principle, the turn of a day separates one sighting from another]. However, if he is not certain whether one occurred one day and the other the next, then there is doubt as to whether he has seen three issues or two. Since in any case he has seen two issues, he is certainly unclean for seven days, as is always the case with a person who saw two issues. However, since it is uncertain whether he has seen two issues or three, he is not liable to bring a sacrifice.
  If he had seen issues on two separate days at twilight, he is in doubt both with regard to defilement and with regard to a sacrifice.  In this case, he saw an issue for two days straight at twilight. It is possible therefore that an entire day interrupted between the first issue and the second. In such a case he wouldn't even be impure. His purity status is therefore doubtful. On the other hand, he might have seen three issues, one of them being divided by the turn of the day into two. Therefore, he might be liable for a sacrifice. His status vis a vis a sacrifice is therefore also doubtful.
  If [he had seen only] one issue at twilight, he is in doubt [also] with regard to [his] defilement.  One issue seen at twilight is enough to create a doubt with regard to his purity status, for the turn of the day could divide the issue into being considered two issues. However, there is no possibility to consider this to be three sightings. Clearly, he is not liable for a sacrifice.
  
  
  
  
  
  Mishnah 1
  
  All persons become unclean through zivah, even converts, even slaves whether freed or not, a deaf-mute, a person of unsound senses, and a minor, a eunuch whether [he had been castrated] by man, or was a eunuch from [the time of seeing] the sun.  The laws of becoming unclean through seeing zivah (zov) apply to any Jew of any status, including converts, freed and non-freed slaves and people who legally are considered as lacking awareness. They apply to all males, even those who have been castrated, either by another human being or were born as eunuchs.
  With regard to a tumtum and an androgynous [person], they place upon him the stringencies for a man and the stringencies for a woman: they defile through blood like a woman, and through eggy [substance]  like a man. Their uncleanness still remains in doubt.  The laws of being a zav apply only to a man and the laws of being a zavah apply only to a woman. They also work differently. Our mishnah asks what to do with two categories of people who exist somewhere in between, neither male nor female? A tumtum does not have signs of being either male or female whereas an androgynous person has both (according to the rabbinic definition). The rule with regard to the stringencies that apply to either sex apply to them. So if they have blood flow, it defiles as it does for a woman. And if they have zov discharge (eggy substance) then they defile as it does for a man. However, the status of their defilement is doubtful. For if they see blood, they might be a male for whom blood does not defile. And if they see a discharge of zov, they might be female for whom such discharge does not defile. Therefore, in either case they only doubtfully defile.
  
  Mishnah 2
  
  Introduction
  Zivah comes only from a genital disease or dysfunction. The rabbis considered it to be in a sense diseased semen (I know, this sounds a bit humorous). It has a different color from semen. If the rabbis could establish that the zivah came from another cause besides some genital disease, then they didn't consider it be zivah. Our mishnah talks about what else we could attribute the zivah to.
  There are seven ways in which a zav is examined as long as he had not become subject to zivah:  When a person sees zivah, he can come to an expert and the expert could tell him that the appearance of the zivah is due to some other cause, not actual genital disease. If they find another reason as to why it occurred, they can keep him from becoming pure. However, this only works before he has become a zav, as we shall see at the end of this mishnah. Once he has already been declared a zav, the zivah can't be attributed to anything else.
  With regard to food, drink, as [to what] he had carried, whether he had jumped, whether he had been ill, what he had seen, or what he had thought.  There are seven other things to which the rabbis attribute the appearance of zivah. Most of these are self-explanatory. Seeing refers to seeing a woman and having some sexual thoughts about her. "What he had thought" refers to having sexual thoughts about a woman. The rabbis also thought that the zivah could have been a result of eating some food, drink or carrying something, perhaps heavy.
  [It doesn't matter] whether he had thoughts before seeing [a woman], or whether he had seen [a woman] before his thoughts.  It doesn't matter whether he had the sexual thoughts before or after he saw the woman in both cases, we can attribute the appearance of zivah to his sexual thoughts and not to genital disease.
  Rabbi Judah says: even if he had watched beasts, wild animals or birds having intercourse with each other, and even when he had seen a woman's dyed garments.  Evidently, Rabbi Judah assumes that a man might be sexually aroused by seeing animals have sex or by seeing colored women's clothing. Therefore, if he saw any of these and then saw zivah, we can attribute it to sexual arousal and not disease.
  Rabbi Akiva says: even if he had eaten any kind of food, be it good or bad, or had drunk any kind of liquid. They said to him: Then there will be no zavim in the world!’ He replied to them: you are not held responsible for the existence of zavim!’  Rabbi Akiva is willing to attribute the appearance of zivah to anything whatsoever. As his students note, this will make it so there will never be any more zavim in the world. Remarkably, Rabbi Akiva responds that if his definition of zivah and why it occurs should make it such that there are no more zavim, then so be it. To me, this is the ultimate statement of Rabbi Akiva's belief that law trumps reality. If he, the rabbi, dictates that we can attribute zivah to eating or drinking anything and it results in there never being any more zavim, then so be it.
  Once he had become subject to zivah, no further examination takes place.  If he has already seen zivah twice, then there is no more room to attribute it to anything else. In other words, these questions must be asked immediately, not after he is already considered a zav.
  [Zov] resulting from an accident, or that was at all doubtful, or an issue of semen, these are unclean, since there are grounds for the assumption [that it is zivah].  If he has a seminal emission at the outset and a little bit of zivah also comes out, this zivah is not impure for one who has an emission does not defile through zivah for a 24 hour period. In other words, until he is decidedly impure the semen purifies the zivah, which is considered to have been an "accident." However, after he has already seen zivah, a seminal emission does not purify the zivah, for we can't assume that the zivah was a result of the semen. Therefore, in this case it counts as seeing zivah.
  If he had at a first [issue] they examine him; On the second [issue] they examine him, but on the third [issue] they don't examine him. Rabbi Eliezer says: even on the third [issue] they examine him because of the sacrifice.  If he saw zivah one time, they examine him as we explained above. If he saw it again, they can examine him again to see if they can attribute it to something else. But if he saw it a third time (without having been examined the first two times), they don't examine him, for after the second time he was already a zav. Rabbi Eliezer says they even examine him after the third time to ascertain that he is truly liable for a sacrifice. If he experienced the third issue for some other reason, then he is not liable for the sacrifice, even though he is a zav.
  
  Mishnah 3
  
  One who had [a discharge of] semen does not defile due to zivah for a period of twenty-four hours. Rabbi Yose says: [only] that day.  As we learned in yesterday's mishnah, if a man has a seminal emission, for the next twenty-four hours any zivah is attributed to the semen; he does not defile as does a zav. Rabbi Yose says that this "grace" period is just during that day, the day on which he had a seminal emission. If the following day he has a flow of zov, he is impure, even if this is less than 24 hours after the seminal emission.
  A non-Jew who had a discharge of semen and then converted, he immediately becomes unclean due to zivah.  When a non-Jew converts, all of the things that happened to him as a non-Jew no longer count towards his status. So if he had a seminal emission before he converted, and then he converted, the seminal emission does not purify the zivah that he sees after he has converted (welcome to Judaism!). This is summed up by the saying that "a person who converts is like a newborn child." He starts afresh and seminal emissions that he had as a non-Jew no longer count (bet you never knew that one before!).
  [A woman] who had [an issue] of blood, or had experienced difficulty [in childbirth], [the time prescribed] is twenty-four hours.  A woman who sees menstrual blood defiles things that she has had contact with in the past 24 hours. This is a halakhah we saw throughout tractate Niddah. A woman who has labor pains cannot be a zavah even if she has seen zivah. However, if there are 24 hours in which she doesn't have pains and then she sees zivah, then she can be considered a woman who has childbirth while she is a zavah (there are special rules concerning this scenario, see Niddah 4:4).
  One who strikes his slave, the "day or two" is twenty-four hours.  The next two sections are here only because they deal with other cases in which a 24 hour waiting period is relevant. If a person strikes his slave and the slave is okay for 24 hours, and then he dies, the owner is exempt (Exodus 21:21). The rabbis understand "a day or two" to be a 24 hour waiting period.
  A dog that eats a corpse's flesh, for three days from one time of day to the same time of day, it is considered to be in its natural state.  If a dog eats the flesh of a human corpse, the flesh continues to defile as human flesh for three days, from the time of day in which it was eaten. After that, it no longer defiles because it is no longer considered to be human flesh.
  
  Mishnah 4
  
  Introduction
  Today's mishnah deals with how a zav defiles things.
  A zav defiles the objects that are lain upon (or sat in five ways, so that they defile people and garments: by standing, sitting, lying, hanging or leaning.  A zav can defile things that are lain upon or sat upon (such as chairs and couches) even though he hasn't touched them. The things that he defiles will then defile other people and clothing (see Leviticus 15:5-6). The five ways are: standing (he stands on the object, even if he doesn't touch it. Sitting and lying (even without touching). "Hanging" refers to a case where the zav is hanging because of the couch or chair. For instance, the chair is on one end of a balance and the zav on the other. If the zav is lifted up by the heavier chair, the chair is now impure. These five things are called "midras hazav." The chair or couch is now a "father of impurity" and it will defile other people and garments. Note that simply touching something is not sufficient he must do one of these five things.
  What he lies upon defiles a person in seven ways, so that he [in turn] defiles garments: by standing, sitting, lying, hanging, or leaning upon it, or by touching or carrying it.  The couch or chair (or other such instrument) upon which he lied or sat (or one of the other ways of conveying impurity listed above) will defile people such that they in turn defile garments. Note that if it defiles garments, these garments do not defile people. The couch or chair defiles by standing on a person, by sitting or lying on a person, by being hanged by a person (see previous section) or by leaning on a person. These five are the same as those above. In addition, it also defiles by touching or by being carried by a pure person.
  
  
  
  
  
  Mishnah 1
  
  A zav and a clean person who sat together in a boat, or on a raft, or rode together on a beast, even though their garments did not touch, behold they are impure through midras.  In this case the zav and a clean person are traveling together on a boat, raft or animal. The clothes of the pure person are defiled by the zav even if they didn't touch. There are two possible explanations for why. First of all, since these things are all moving, it is possible and even likely that the zav did indeed lean upon the clean person's clothing. Alternatively, the clean person could have caused the ship, raft or animal to lean in his direction which would cause the zav to go up. This is "hanging" explained in yesterday's mishnah.
  If they sat together on a plank, on a bench or on a bed-frame, or on a beam, when these were not fixed tightly, [Or] if they had both climbed a weak tree, or [were swaying] on a weak branch of a strong tree; Or if they were both [climbing] on an Egyptian ladder which was not secured by a nail; Or if they sat together on a bridge, rafter or door, not secured by clay, they are unclean. Rabbi Judah says that they are clean.  In all of these cases, the zav and the clean person sit on something loose. Since the zav's moving would cause the clean person to move as well, the clean person is defiled. This is called defilement through shifting. An alternative explanation is that this is the same as the case in section one. The clean person might cause the zav to go up and this is considered "hanging."
  
  Mishnah 2
  
  Introduction
  Today's mishnah deals with a series of cases in which a zav and a clean person are jointly performing some action. In each case, there is one opinion that holds that the clean person has been defiled, or might have been defiled, and there is one opinion that holds that only if the act was done under specific conditions is he considered defiled.
  If they were both closing or opening [a door], [the clean person and his clothes are unclean]. But the sages say: [he is not unclean] unless one was shutting and the other opening [it].  According to the first opinion, if they were both either opening or closing a door then the zav has shifted the clean person by applying pressure to the door. The clean person and his clothes are defiled. The sages hold that this is true only if they are pushing against each other. In such a case, it is likely that one has moved the other. But if both are opening or closing, then it is more likely that neither has moved the other, so the clean person remains pure.
  If one was lifting the other out of a pit [the clean person and his clothes are unclean]. Rabbi Judah says: only if the clean person was pulling out the unclean one.  According to the first opinion, if the zav and pure person are helping each other climb out of a pit, then it is likely that the zav has lifted or shifted in some way the pure person. Therefore, he is defiled. Rabbi Judah says that the pure person is defiled only if the pure person is helping the zav get out of the pit. In such a case, the zav may have leaned on the pure person and defiled him. But if the zav is helping the pure person out of the pit, he is not defiled. Evidently, Rabbi Judah is lenient and holds that the zav must lean on the pure person to defile him. Simply moving him does not cause defilement. Note that Rabbi Judah was also lenient in yesterday's mishnah.
  If they were twisting ropes together [the clean person and his clothes are unclean]. But the sages say: unless the one pulled one way and the other pulled the other way.  Again, the first opinion holds that by twisting ropes together the zav may have leaned upon or shifted the clean person and thereby defiled him. The sages rule that they have to be pulling in opposite directions, as was the case with the door in section one.
  If they were both weaving together, whether they were standing or sitting, or grinding wheat, [the clean person and his clothes are unclean]. Rabbi Shimon says [the clean person] in every case is pure, except where they [both] were grinding with a hand-mill.  The first opinion holds that weaving or grinding together causes the zav to defile the clean person, either because he leans on him or he shifts him. Rabbi Shimon rules more leniently. The only case of defilement is when they grind together with a hand-mill.
  If they [both] were unloading or loading a donkey, they are unclean if the load was heavy, but clean if the load was light.  If they are both unloading a donkey and the load is heavy, then the zav would likely have leaned on the pure person and defiled him. But if the load is light, they could both unload independently and one has not leaned on the other.
  In all cases, however, they are clean for members of the synagogue, but are unclean for terumah.  In all of these cases, we can't be certain that the pure person is defiled. Therefore, he can sit with other members of the synagogue who are eating their non-sacred food in a state of purity. Since this behavior is only a stringency, and is not required by law, we can be lenient and let him eat with them. However, the Torah prohibits eating defiled terumah. Therefore, he cannot eat terumah. This last clause basically serves to clarify that in all of these cases the status of his impurity is doubtful, not certain.
  
  Mishnah 3
  
  If the zav and the clean person sat together in a large boat: (what is considered a large boat? Rabbi Judah said: one that does not sway with a man's, or if they sat on a plank, bench, bed-frame, or beam when these were firmly secured; Or if they both climbed a strong tree, a firm branch, or a Tyrian ladder, or an Egyptian ladder fixed by a nail; Or if they sat on a bridge, rafter or door, when these were fastened with clay, even if only at one end, they remain clean.  In all of these cases, since the things upon which the zav and clean person sat were stable, the zav has not moved the clean person. Therefore, the clean person remains clean. Note that most of this list is simply the opposite of those things listed in mishnah one. Either they were firmly secured, they were fixed by a nail or they were fastened in place by clay. In mishnah one, the opposite was always the case the various items were loose. Therefore the pure person became defiled.
  If the clean one struck the unclean one, he still remains clean. But if the unclean one struck the clean one, he is impure; for [in that case] if the clean one drew back, the unclean one would have fallen.  A clean person who strikes a zav remains clean because the zav has not moved the clean person. While it is possible that when hitting him the clean person leaned on the zav, since this is not certain, he remains clean. However, if the zav strikes the clean person he is in a sense leaning on the clean person, for if the clean person moves when the zav strikes him, the zav would fall down (and be embarrassed). Leaning on the clean person defiles him.
  
  
  
  
  
  Mishnah 1
  
  Rabbi Joshua said: if a menstruant sat in a bed with a clean woman, [even] the cap on her head contracts midras uncleanness. And if she sat in a boat, the vessels on the top of the mast [also] contract midras uncleanness.  A niddah defiles in the same way that a zav and a zavah do. According to the rabbis in 3:1, when a niddah (or a zav) sits in the same bed (or boat or carriage) as does a pure person she defiles the other person's clothes because she might have stepped on them. Rabbi Joshua says that even the cap on the other person's head is defiled, even though the niddah definitely didn't step on the other woman's head. Similarly, if she sits in a boat, even the vessels on the top of the mast are unclean, even though she clearly didn't step on them. Rabbi Joshua rules more strictly than do the other sages.
  If there was [on the boat] a tub full of clothes: If their weight was heavy, they become unclean, But if their weight was light, they remain clean.  This section is also part of Rabbi Joshua's opinion. I have explained the section according to Albeck. If the clothes were heavy, then there is a possibility that they pushed the boat down on one side and therefore lifted up the niddah who was on the other side. As we learned in 2:4, if a zav (or zavah or niddah) is "hung" by something, the other thing becomes impure. However, if the tub of clothes is light, they remain pure because they wouldn't have caused the boat to shift. Note that Rabbi Judah does not automatically make the clothes impure, as he did in section one. Albeck explains that Rabbi Judah rules strictly only with regard to single pieces of clothing. When it comes to a tub of clothing, he rules more in line with the other sages.
  If a zav knocked against a balcony and thereby caused a loaf of terumah to fall down, it remains clean.  Although it seems that the zav caused the loaf of terumah to fall and thereby defiled it, the rabbis don't think that the zav really could have caused the stone balcony to shift. Rather, it must have been some movement in the ground that caused the loaf to fall. Therefore, it remains pure.
  
  Mishnah 2
  
  If he knocked against a strong beam, a window-frame, water-pipe, a shelf, even though it was fixed with ropes, or an oven, a flour container, the lower mill-stone, the base of a hand-mill, or the se'ah measure  of an olive-grinder, [the loaf remains clean].  In all of these cases there was a loaf of terumah bread sitting on one of these large items. A zav knocked against one of them and the loaf fell down. Since all of these items are set in their place we can attribute the loaf falling down to some force other than the zav. As we learned in yesterday's mishnah, we can assume that the ground shifted.
  Rabbi Yose adds: also [if he knocks] against the beam of the bath-keeper, it remains clean.  Rabbi Yose adds that the same halakhah applies to the "beam of a bath-keeper." This is the beam upon which it was customary for the bath-keeper to sit.
  
  Mishnah 3
  
  If he knocked against a door, doorbolt, lock, oar, mill basket,   or against a weak tree, or weak branch of a strong tree, or against an Egyptian ladder unsecured by nails, or against a bridge, beam or door, not made secure with clay, they become unclean.  In all of these cases the zav knocks against something and thereby causes an object to fall off of it. Since these things are loose or weak, we can assume that the zav caused the object to fall and therefore the object becomes unclean. Many of these items were mentioned in mishnah 3:1 (and their opposites in 3:3). [Note that door seems to have crept into this mishnah twice. Clearly a mistake it probably belongs in the first half and not the second].
  [If he knocked] against a chest, box or cupboard, they become unclean. Rabbi Nehemiah and Rabbi Shimon declare them clean in these cases.  According to the first opinion these objects are not so sturdy and therefore it is likely that the zav caused them to fall. Rabbi Nehemiah and Rabbi Shimon believe that they are sturdy and therefore if something falls off of them, it probably was not due to the zav.
  
  Mishnah 4
  
  Introduction
  A zav who lies on something makes it unclean. Our mishnah deals with cases where a zav lies on multiple items do they all become impure, or can we isolate which one(s) he really laid upon?
  A zav who lays across five benches, or five money-belts: If lengthwise, he [makes them] unclean; But breadthwise, they are clean.  If the zav lies across the length of five benches or money-belts it is possible that at any one time most of his weight was on one of the benches or belts. Therefore, they are all impure. However, if he lies on them across their breadth then his weight is distributed equally among them all. Since he didn't lie on any one of them, they all remain pure.
  If he slept [on them],   and it was doubful that he had turned over onto them, they are unclean.  If he slept on the benches or the money-belts then they are impure even if he slept across their breadth because we don't know if he turned around a lot while sleeping. Since he might have put all of his weight on one, they are all impure.
  If he was lying on six seats, with two hands on two [seats], two feet on another two, his head on one, with his body on another one, only that one on which his body lay   is rendered unclean.  Since the majority of his mass was on one of the seats, only that seat is unclean.
  If [a zav] stood on two seats: Rabbi Shimon says: if these were distant one from the other, they remain clean.  If the two seats are far apart from the other, then the zav would need both of them to stand on. Take one away and he would fall down. Since neither would support the full weight of the zav each remains pure. But if they were close together, at times the zav could shift all of his weight to one and then it would be defiled.
  
  Mishnah 5
  
  Ten cloaks one on top of the other, if he sat on the uppermost one, all are unclean.  When a zav sits (other versions read sleeps) on a pile of something, all of the things upon which he sat become impure, even though he only touched the upper most one.
  A zav who was one one scale of a balance and in the other scale opposite there were objects fit to sit or lie upon: If the zav pushed them up, they are clean. But if they pushed him up, they are unclean. Rabbi Shimon says:   if there was one object it becomes unclean, but if there were many   they remain clean, since none of them had borne the greater part [of the zav's weight].  In mishnah 2:4 we learned that if another object causes a zav to be lifted up, that object becomes impure. So imagine a huge balance (maybe a seesaw?!) with a zav on one side and on the other side are things that one lies or sits upon. If he lifts them up they do not have midras impurity, because he didn't "lean" on them. However, since he did carry them they do have some impurity, just a lesser degree. If they push him up then he is considered as having leaned upon them, and they are impure. Rabbi Shimon says that if there are multiple objects on the opposite side of the scale, then they have all divided up his weight equally. Since none of them bear the majority of his weight they all remain pure.
  
  Mishnah 6
  
  If a zav [sat] in one scale of the balance, while food and liquids were in the other scale, [the latter become] unclean.  The food or liquids that are on the other side of the scale are lifted up by the weight of the zav. However, they do not have midras impurity, even if they are heavy enough to lift up the (lightweight) zav because midras impurity is only conveyed to objects that are designed to be sat or laid upon. Food and liquid are never susceptible to midras impurity. However, they are impure with first degree impurity, which is lighter than midras impurity.
  In the case of a corpse, everything remains clean except for a man.  The mishnah now begins to compare impurity conveyed by a dead body with the impurity conveyed by a zav. When a dead body is on one side of a balance and something else is on the other side, whatever is on the other side is not defiled because a dead body does not defile by sitting, laying or shifting without contact.
  This is [an example of] the greater stringency applying to a zav than to a corpse; and there is a greater stringency in the case of a corpse than a zav.  This is the general statement that sums up this mishnah sometimes the rules are stricter for a zav and sometimes they are stricter for a corpse. This is typical of the Mishnah it loves to compare laws governing different yet similar cases.
  For whereas the zav defiles all objects on which he sits or lies upon, so that these likewise convey uncleanness to people and garments, and he conveys to what is above him madaf uncleanness, so that these in turn defile food and liquids. Whereas in the case of a zav no such uncleanness is conveyed.  There are two types of uncleanness conveyed by a zav that are not conveyed by a corpse. The first is that a zav conveys uncleanness by sitting or lying on things, such that those items now convey uncleanness even to people and clothing. Furthermore, a zav defiles things that are placed on top of him even if he doesn’t touch them. This impurity is called "madaf" and it probably comes from the word for "shelf" madaf in Hebrew. This impurity is relatively light for these items defile other food and liquids but they wouldn't defile clothing and people. Again, a dead body wouldn't defile in this way.
  Greater stringency is also found in the case of a corpse, since it can convey uncleanness by overshadowing, and it defiles seven days’ defilement, whereas in the case of a zav no such uncleanness is conveyed.  A dead body does defile by overhanging (an ohel). We learned about this extensively in Tractate Ohalot. This means that if something hangs over both a corpse and a clean object the impurity of the corpse goes to the clean object. A zav doesn't defile in this way.
  
  Mishnah 7
  
  If he sat on a bed and there were four cloaks under the four legs of the bed, all become unclean, since the bed cannot stand on three legs; But Rabbi Shimon declares them clean.  Since the bed can't stand without all four legs, we have to look at each leg of the bed as if it carries the full weight of the zav. Therefore, all four cloaks are impure because he sat on all four of them. Rabbi Shimon says that all four of the cloaks are clean. This is because none of them bears the zav's full weight. Since his weight is evenly distributed among the four legs, they all remain pure.
  If he rode on a beast and there were four cloaks under the legs of the beast, they are clean, since the beast can stand upon three legs.  In contrast to a table, an animal can stand on three legs, so any one leg is not necessary for bearing the weight of the zav.
  If there was one cloak under its two forelegs or its two hindlegs, or under a foreleg and a hindleg, it becomes unclean.  But a beast cannot stand on two legs. Therefore, if the cloak is underneath any of the two legs, then it is considered to bear the full weight of the zav and it is unclean.
  Rabbi Yose says: a horse conveys uncleanness through its hindlegs and a donkey through its forelegs, since a horse leans upon its hindlegs and a donkey upon its forelegs.  According to Rabbi Yose a horse bears its weight on its hindlegs and a donkey's weight is borne on its forelegs. Therefore, if the cloak is under the horse's hindlegs or the donkey's forelegs it is impure. But if not, it remains pure.
  If he sat on a beam of an olive-press, the vessels in the olive-press receptacle are unclean.  Since the zav presses down on the olive press, the olives are impure.
  [If he sat] on a clothing press, the garments beneath it are clean. Rabbi Nehemiah declares them unclean.  Unlike an olive press, a clothing press is already closed tight. When the zav sits on the clothing press, he doesn't really press down on the garments. Therefore, they remain clean. Rabbi Nehemiah holds that the zav does press down on the clothing press and the clothing inside and therefore they are defiled.
  
  
  
  
  
  Mishnah 1
  
  One who touches a zav, or whom a zav touches, who moves  a zav or whom a zav moves, defiles by contact food and liquids and vessels that are rinsed, but not by carrying.  A zav defiles through contact or through moving something or being moved by something. This mishnah discusses the level of impurity of the person whom he defiled. Such a person defiles food, liquids and vessels that "are rinsed" meaning vessels that can be purified by being put in a mikvah. This would include basically all vessels except earthenware, which can't become pure in a mikveh. The person defiled by a zav defiles only through actual contact she/he does not defile through carrying. She also does not defile other people just food and things.
  A general principle was stated by Rabbi Joshua: anyone that defile garments  while still in contact [with their source of uncleanness] also defiles foods and liquids so as to become [unclean] in the first grade, and the hands  so that they become [unclean] in the second grade; but they do not defile people or earthenware vessels.  Rabbi Joshua formulates a general principle meant to aid in determining the level of impurity of certain people mentioned in the Torah. The Torah says about certain people, for instance one touched by a zav, that he must wash his clothes (see for instance Leviticus 15:5-11, 21-22, 27). When he is actually touching the zav or something the zav laid upon, his level of impurity is relatively high. He defiles food and liquids so that they have first degree impurity. And if he touches the hands of another person he gives them second degree impurity (we will return to the topic of hand impurity in the next tractate). However, he doesn't defile people or earthenware vessels, as was stated in section one.
  After they separated from their source of uncleanness they defile liquids so as to become [unclean] in the first grade, and food and the hands so that they become [unclean] in the second grade, but they do not defile garments.  This is a continuation of Rabbi Joshua's general principle. Once the person has separated from the source of impurity, his ability to defile is lowered. He still defiles liquids so that they have first degree impurity. This is because liquids have a higher degree of susceptibility to impurity. However, he only defiles food and hands so that they have second degree impurity. This means that the food is only affected if it is terumah. If it is regular produce, it is unaffected. These people do not defile garments or any other vessels for they are treated as if they have first degree impurity and people with first degree impurity do not defile vessels or people.
  
  Mishnah 2
  
  Introduction
  Today's mishnah provides some general rules as to how a zav defiles things that are either above him or below him that he does not touch.
  They said yet another general principle: All that is carried above a zav becomes defiled, but all those things above which he is carried are clean except objects on which he can sit or lie upon, and a person.  This section describes the general rule. Anything above a zav is defiled but things that are below him are defiled only if they were meant for sitting or lying upon, except for a person who carries a zav who is also defiled. The rest of the mishnah will illustrate this principle.
  How so? If a zav had his finger beneath a layer of stones and one that was clean was above, he conveys uncleanness at two [degrees of remove] and disqualifies [terumah] at one [further remove]. If he separated [from the source of uncleanness] he still defiles at one remove and disqualifies [terumah] at yet one [further remove].  The mishnah now begins to demonstrate how this defilement is conveyed. A zav has his finger underneath a row of stones (ouch!) and on top of the row of stones is a pure person. The pure person is considered to be carried by the zav. The pure person now becomes a "father of impurity." Anything he touches will have first degree impurity and anything touched by it will have second degree impurity. If the object with second degree impurity touches terumah the terumah is disqualified (see Kelim 19:4). This is in general a description of the defiling power of one who is considered to be a father of impurity. If the pure person moves away from the row of stones or the zav removes his hand then the pure person will only have first degree impurity. Anything he touches will have second degree impurity and any terumah that it touches will be disqualified.
  If the unclean one was above, and the clean person below, he defiles at two [removes], and disqualifies [terumah] at yet one [further remove]. If he separated [from the source of uncleanness], he defiles at one [remove] and disqualifies [terumah] at yet one [more remove].  The same rules apply if the zav was on top of the row of stones and the finger of the pure person was below.
  If foods or liquids, or objects on which he could sit or lie upon or other articles were above, they defile at one remove, and disqualify [terumah] at one [further remove]. If they had become separated [from the source of uncleanness], they defile at one [remove] and disqualify [terumah] at one [more remove].  If the zav is below and something that is meant to be sat upon or food or any article (called in Hebrew a madaf) was above, he defiles them with only first degree impurity. This doesn't change if the source of impurity is removed. [I should note that I have explained this according to most commentators, but they printed editions of the Mishnah have a different reading].
  All objects fit to sit or lie upon that were below defile at two [removes], and disqualify [terumah] at one [more remove]. If they had become separate [from the source of uncleanness], they defile at two [removes] and disqualify [terumah] at one [more remove] Foods and liquids and other articles that are below, remain clean.  However, if the zav is above and something meant to be sat or lied upon is below him, he defiles them such that they become fathers of impurity. Even if the source of impurity is removed, they remain fathers of impurity. However, he only conveys impurity to things that are meant to be sat or lied upon. If below him are foods, liquids or other articles not meant to be sat upon, they remain pure.
  
  Mishnah 3
  
  Introduction
  This mishnah compares how three objects, (1) something that a zav has sat or laid upon, (2) carrion and (3) a piece of a human corpse, defile without contact.
  Whatever carries or is carried by objects on which one sits or lies upon remain clean, except for a person.  Anything that carries an object that was laid upon by a zav without touching it or is carried by it, meaning it was above and the thing the zav laid or sat upon was below, remains clean. The only exception is a person. If a person carries or is carried by something upon which a zav sat or laid, the person is impure, even if he didn't touch it.
  Whatever carries or is carried by carrion is clean, except for one that shifts it. Rabbi Eliezer says: also one that carries it.  The mishnah compares this situation with that of carrion meat from an animal that had not been slaughtered properly. Whatever carries or is carried upon carrion (no pun intended, I promise) remains pure (as long as he didn't touch it). The only exception is a person who shifts the carrion. He is impure, even if he doesn't touch it. Rabbi Eliezer says that also one who carries carrion is impure, even if he didn't move it.
  Whatever carries or is carried upon a corpse remains clean, except for one that overshadows, or a person when he shifts it.  A corpse or piece thereof also doesn't convey impurity to someone through carrying or being carried. But it does convey impurity through overshadowing or through shifting even if the corpse has not been touched.
  
  Mishnah 4
  
  If part of an unclean person rests upon a clean person, or part of a clean person upon an unclean person, or if things connected to an unclean person [rest] upon a clean person, or if things connected to a clean person upon one unclean, he becomes unclean.  If part of a zav, such as his finger, rests upon a clean person, or vice versa, the clean person is defiled. "Things connected" to a person refer to his hair, teeth or fingernails. They are not flesh, but they are part of a person. The mishnah teaches that even if one of these parts rests upon another person, impurity is conveyed.
  Rabbi Shimon says: if part of an unclean person is upon a clean person, he is unclean;   but if part of a clean person is upon one that is unclean, he is clean.  Rabbi Shimon rules that impurity is conveyed only if part of the unclean person, the zav, is on the clean person. This is because this is the typical way that impurity is conveyed by a zav by him sitting or lying or resting upon something. But the opposite is not true. If a clean person rests a part of his body on a zav, he remains clean.
  
  Mishnah 5
  
  If an unclean person rests upon part of an object fit to lie upon, or a clean person   rests upon part of an object fit to lie upon, it becomes unclean.  There are two situations referred to here. In the first case most of the zav (the unclean person) is resting on part of a clean object that is fit to lie upon. In the second case, most of the clean person is resting upon part of an object fit to lie upon that has been defiled by a zav. In both cases the impurity is conveyed, either to the object in case one or the person in case two. The mishnah will explain below in section three that the impurity of the zav can enter the entire object through the small part of the object upon which the zav lies. It can also go out of the object through the small part of the object upon which the pure person lies.
  If part of an unclean person rests on an object fit to lie upon, or part of a clean person rests upon an object fit to lie upon, it remains clean.  But if only a small part of the unclean person is on the object or only part of the clean person is on the unclean object, then he remains pure, because the object is only defiled if it bears most of the weight of the zav (see 4:4). Similarly, the pure person is not defiled unless the impure object bears most of his weight.
  Thus we find that impurity enters it and goes out of it by its lesser part.  This section provides the rule that explains section one impurity can go in and out of the object fit to lie upon even threw a small part of that object.
  Similarly, if a loaf of terumah was placed upon an object fit to lie upon [that was unclean] and there paper in between, whether it was above or below, it remains clean.  The word "similarly" does not really belong here. It is missing in some versions of the Mishnah. In mishnah 3 we learned that impurity through "carriage" being carried without touching is conveyed only to a human being by an object upon which a zav has lain. So if a loaf of terumah is either on top of an object which a zav lied upon or that object is on top of it, and there is a piece of paper separating them so that they don't touch, the loaf of terumah remains pure. The loaf of terumah is impure only if it touches the object.
  Similarly, in the case of a stone with scale disease it remains clean. Rabbi Shimon pronounced such a case unclean.  The same is true if the loaf of terumah is on top of a stone that has contracted a "nega" scale disease. As long as the paper prevents contact, the loaf is pure. Rabbi Shimon says that in this case the loaf of terumah is impure. A stone with a nega conveys impurity through being in an ohel overshadowing. Since the stone overshadows the loaf or vice versa, the loaf is impure.
  
  Mishnah 6
  
  He who touches a zav, or a zavah, a menstruant, or a woman after childbirth, or a metzora, or any object on which these had been sitting or lying, conveys uncleanness at two [removes] and disqualifies [terumah] at one [further remove].  The person who touches one of these five people (a metzora is one with skin disease, see Negaim) or something that sat or laid upon is a "father of impurity." Anything he touches has first degree impurity and anything it touches has second degree impurity. Terumah that touches something with second degree impurity is disqualified.
  If he separated, he still conveys uncleanness at one [remove], and disqualifies [terumah] at one [further remove].  When he separates from the source of impurity his level of impurity is lowered to first degree impurity. He conveys impurity at one only remove and disqualifies terumah at two removes.
  This is true whether he had touched, or had shifted, or had carried, or was carried.  The above is true no matter how he contacted the impurity. He need not actually touch the source of impurity.
  
  Mishnah 7
  
  If one touches the discharge of a zav, his spittle, semen or urine, or the blood of a menstruant, he conveys uncleanness at two [removes], and disqualifies [terumah] at one [more remove];  Liquids from a zav's body, including his genital discharge, his spit, his semen and his urine defile as does the zav himself. They make one who touches or moves them into a "father of impurity."
  If he separated,   he defiles at one [remove] and disqualifies [terumah] at one [more remove].  Once he separates from the source of impurity, he has first degree impurity.
  This is the case whether he had touched or moved it. Rabbi Eliezer said: also if he had carried it.  These substances defile only through contact and shifting. They do not, according to the first opinion, defile by carrying or by being carried. Rabbi Eliezer disagrees and holds that they do defile one who carries them. This was the same dispute that Rabbi Eliezer had with the sages in mishnah three.
  
  Mishnah 8
  
  If he carried something which was ridden upon, or if he was carried on it, or he had shifted it, he defiles at two [removes], and disqualifies [terumah] at one [more remove]; But if he became separated [from the uncleanness], he defiles at one [remove] and disqualifies [terumah] at one [more remove].  A person who carries or is carried by something upon which a zav rode upon becomes a "father of impurity." This is because it is written in the Torah that he must wash his clothes (Leviticus 15:10; see 5:1). Therefore he defiles at two removes and disqualifies terumah at one more remove. Once he separates from the source of impurity, he has only first degree impurity. Note that if he touches something rode upon by a zav, he only has first degree impurity.
  If he carried nevelah (, or the hatat waters sufficient for a sprinkling, he defiles at two [removes], and disqualifies [terumah] at one [more remove]; But if he became separated, ,he defiles at one [remove] and disqualifies [terumah] at one [more remove].  The same is true for one who carries (actually shifts, see mishnah 3) nevelah (an animal slaughtered in a non-kosher manner) or one who carries the "hatat waters" (the waters into which the ashes of the red heifer had been mixed). This last rule is also found in Parah 12:5.
  
  Mishnah 9
  
  Introduction
  Today's mishnah talks about a person who eats the nevelah (carrion) of a clean bird. In Toharot 1:1 we learned that this carrion defiles him once it is in his gullet. There are more details about the laws governing the carrion of a clean bird in that mishnah, for those of you who are very interested.
  He who ate nevelah of a clean bird, and it still is in his gullet, defiles at two [removes], and disqualifies [terumah] at one [more remove].  When the nevelah of the clean bird is in his gullet, he is a father of impurity.
  If he put his head within the air-space of an oven, the oven remains clean.  Despite the fact that he is a father of impurity, if he puts his head into the air-space of an oven, he doesn't defile the oven. This is because a person who is defiled such that he must wash his clothes does not defile earthenware vessels. Note that the oven can generally be defiled by something impure entering its air space. Furthermore, once the carrion is in the gullet of the person, it only defiles the person. Because it's inside him it doesn't go out of him and defile the oven.
  But if he vomited or swallowed it, he defiles at one [remove] and disqualifies [terumah] unfit at one [more remove].  The nevelah only makes him into a father of impurity when in it is in his gullet. If he expels it, or swallows it, he goes down a notch in impurity to having only first degree impurity.
  But as long as it is still in his mouth, until he swallows it, he remains clean.  When it's just in his mouth, he is clean. It only begins to defile him once it has entered his gullet.
  
  Mishnah 10
  
  He who touches a dead sheretz, or semen, or he that has suffered corpse uncleanness, or a metzora during his days of counting,  or hatat waters of insufficient quantity with which to perform the sprinkling,  or carrion, or an object ridden upon [by a zav], defiles at one [remove] and disqualifies [terumah] at one [more remove].  All of these substances are "fathers of impurity." One who touches one of them contracts first degree impurity. This same list was mostly found in Kelim 1:1, so one can find a more detailed explanation there. They also defile only by contact and not by carrying. Finally, none of these says that the person must wash his clothes.
  This is the general principle: anyone who touches anything that according to the Torah is a "father of uncleanness" defiles at one [remove] and disqualifies [terumah] at one [more remove], except [for the corpse] of a human.  The only exception to this general rule is one who touches a dead body. Such a person is a "father of impurity" and therefore defiles at two removes and disqualifies terumah at one additional remove.
  If he had become separated, he defiles at one [remove] and renders [terumah] unfit at one [more remove].  In all of these cases, once he separates from the source of impurity he has "first degree impurity." This is true even if the source of impurity was a dead body. Since he has separated from it, his impurity is reduced.
  
  Mishnah 11
  
  He who has had a seminal emission is like one who has touched a dead sheretz.  This mishnah compares the impurity levels of various people. A man who has had a seminal emission has the same rules of impurity as one who touched a dead sheretz. As we learned in yesterday's mishnah, such a person has first degree impurity.
  And one who has had sex with a menstruant is like one who has suffered corpse uncleanness.  But a person who has had sex with a niddah, a woman while menstruating, has a higher degree of impurity he is a father of impurity. Note that all of these laws are learned from midrashim on the Torah. They are in no way value statements, saying that having a seminal emission is akin to touching a dead sheretz or that having sex with a menstruant is worse (although it is forbidden). The mishnah is only interested in comparing levels of impurity.
  But one who has had sex with a menstruant is more stringent in that he conveys minor grades of uncleanness to what he lies or sits upon, so as to make foods and liquids unclean.  A man who has sex with a menstruant has certain purity stringencies related to him that do not relate to a person who has corpse impurity. The former conveys a light form of impurity to anything he sits or lies upon in order for it to defile food or liquids (see Kelim 1:3).  A person with corpse impurity does not defile in this manner, unless he touches that which he sits or lies upon.
  
  Mishnah 12
  
  Introduction
  The final mishnah of this tractate (I'm sure you're sad we're done) discusses what things disqualify terumah. These things don't actually defile the terumah. Rather, the rabbis added a layer of stringency with regard to their impurity such that they would render terumah unfit for use.
  The following disqualify terumah:One who eats foods with first degree uncleanness; Or one who eats food with second degree uncleanness; And who drinks unclean liquids.  From Torah law (deorayta) food and liquid cannot defile a person. Nevertheless, the rabbis decreed that one who eats impure food or drinks impure liquids should be defiled enough such that he would disqualify terumah. This seems to be a way to discourage people who want to eat terumah (kohanim) from eating or drinking impure foods and liquids.
  And the one who has immersed his head and the greater part of him in drawn water; And a clean person upon whose head and greater part of him there fell three logs of drawn water;  In order to distinguish between the purity imparted by the waters of the mikveh (which cannot be drawn), and waters that are drawn, the rabbis decreed that a person who either immersed in drawn waters or upon whom drawn waters fell would disqualify terumah. For more information on this see Toharot 4:11.
  And a scroll [of Holy Scriptures], And [unwashed] hands;  We will learn more about these two categories when we learn Tractate Yadayim (after Tevul Yom, which we start learning tomorrow).
  And one that has had immersion that same day;  Luckily, the very next tractate is about this category of person, so stay tuned.
  And foods and vessels which have become defiled by liquids.  Liquids have greater power to defile than do solids. So if clean food or a vessel has contact with an unclean liquid, the clean food or vessel remains clean but it disqualifies terumah. Congratulations! We have completed Tractate Zavim! As I always write, it is a tradition at this point to thank God for helping us finish learning the tractate and to commit ourselves to going back and relearning it, so that we may not forget it and so that its lessons will stay with us for all of our lives. Tractate Zavim was not easy, that's for sure, perhaps one of the most obscure and strange topics we've talked about yet. To be honest, I'm not even sure what the larger lessons are that I would draw from the tractate as a whole. Perhaps I might end with some speculation as to why the Torah states that abnormal genital discharge (zivah) defiles. Much has been written about the subject of impurity, and there are many conflicting theories that attempt to explain why things are impure and others are not. In my opinion, the most cogent theory is that impurity seems to be connected largely to moments of birth and death. Birth and death are natural processes in life, but they are fraught with danger and power. Abnormal genital discharge is almost like death or at least as the Torah may have perceived it to be so. The material was supposed to have the power to create life (semen) but something went wrong. It is also likely that impurity marks transitions. Impurity is neither good nor bad there is nothing wrong with being impure. But being impure has symbolic significance, and at times, impurity is especially powerful when something is out of place. While this may not explain all forms of impurity, it does explain some of them. For further reading I would suggest looking at the works of Mary Douglas, Jacob Milgrom or Jonathan Klawans.  Impurity can be a much more interesting subject than you might have thought. As always, a hearty yasher koach upon completing the tractate and keep up the good work. Tomorrow we begin Tevul Yom.