אדם שמציל על טומאה שבתוכו מלטמא אינו דין שמציל על טהרה שבתוכו מליטמא
Then with regard to a person, who does shield the impurity of a piece of a corpse contained within him from imparting impurity to other items in the same tent, as the Gemara derived above, is it not logical that he shields a pure item contained within him from being rendered impure?
מה לכלי חרס שכן אין מטמא מגבו תאמר באדם שמטמא מגבו
The Gemara challenges the inference: What is notable about an earthenware vessel? It is notable in that it cannot become impure through a source of impurity coming in contact with its exterior. Can you say, then, that it is comparable to a person, who can become impure through a source of impurity coming in contact with his exterior? Since here the halakhot concerning impurity of a person are more stringent than those concerning an earthenware vessel, one cannot apply to a person a leniency with regard to an earthenware vessel.
אטו אנן מגבו קאמרינן מתוכו קאמרינן
The Gemara responds: Is that to say we are speaking of rendering an item impure through a source of impurity coming in contact with its exterior? We are in fact speaking of where the impurity comes in contact with its interior. For such cases, it is reasonable to compare the case of a person with an earthenware vessel.
אדרבה כלי חרס חמור שכן מטמא מאוירו
The Gemara adds: On the contrary, the contraction of impurity by an earthenware vessel is more stringent than that of a person, as it becomes impure through the presence of a source of impurity in its airspace, even if the source does not touch the vessel itself. By contrast, a person is rendered impure from a source of impurity in his airspace, e.g., in his mouth, only if it actually touches him, and the a fortiori inference remains valid.
אשכחן בלוע דלמעלה בלוע דלמטה מנלן קל וחומר ומה למעלה שאינו עושה עיכול מציל למטה שעושה עיכול אינו דין שמציל
The Gemara asks: We found a source for the halakha that an impure item encapsulated in a body that entered it from above, i.e., through the mouth, does not impart impurity. From where do we derive that an impure item encapsulated in a body that entered it from below, i.e., through the rectum, also does not impart impurity? The Gemara answers: It is derived through an a fortiori inference: And if, when the impure item enters from above, through the mouth, which is a place that does not digest the food, the body nevertheless shields the impure item from imparting impurity, then with regard to a case where the impure item enters from below, which is a place that does digest food, is it not logical that the body should shield it from imparting impurity?
כלום עושה עיכול למטה אלא על ידי מעלה אפי' הכי עיכול דלמטה רב
The Gemara challenges the basis of the inference: Isn’t digestion performed below only by means of the chewing and digestive functions of the body above? The Gemara explains: Even so, the digestion performed below is greater than that performed above.
אשכחן בלוע דאדם בלוע דבהמה מנלן קל וחומר ומה אדם שמטמא מחיים מציל בבלוע בהמה שאינה מטמאה מחיים אינו דין שתציל בבלוע
The Gemara asks: We found a source for the halakha that an impure item encapsulated in the body of a person does not impart impurity; from where do we derive that an impure item encapsulated in the body of an animal does not impart impurity? The Gemara answers: It is derived through an a fortiori inference: If the body of a person, who can impart impurity even while he is still alive, e.g., if he is a leper or a zav, nevertheless shields the impure item encapsulated inside him from imparting impurity, then with regard to an animal, which does not impart impurity while it is alive, is it not logical that it should shield an impure item encapsulated inside it from imparting impurity?
מה לאדם שכן צריך שהייה בבית המנוגע תאמר בבהמה שאינה צריכה שהייה בבית המנוגע
The Gemara challenges the inference: What is notable about the impurity of a person? It is notable in that if he entered a leprous house, in order for his garment to be rendered impure he needs to remain in the leprous house for a minimal period of time (see Leviticus 14:33–53). Can you say, then, that it is comparable to an animal, which does not need to remain in a leprous house for a minimal period of time? Rather, any utensils placed upon it are rendered impure immediately upon its entry. Since here the halakhot concerning impurity of an animal are more stringent than those concerning a person, one cannot necessarily apply to an animal a leniency with regard to a person.
בהמה דאינה צריכה שהייה בבית המנוגע למאי הלכתא לכלים שעל גבה אדם נמי לא בעי
The Gemara responds: When it is stated about an animal that it does not need to remain in a leprous house for a minimal period of time, with regard to what halakha was that said? A living animal itself cannot be impure. Perforce, the statement is referring to utensils that are placed upon its back, and they are rendered impure immediately upon entry. But in this regard there is no difference between animals and people: A person as well does not need to remain in the leprous house for a minimal period of time in order to render impure any utensils placed on his back. Rather, they are rendered impure immediately upon entry.
דתנן הנכנס לבית המנוגע וכליו על כתפיו וסנדליו וטבעותיו בידיו הוא והן טמאין מיד היה לבוש כליו וסנדליו ברגליו וטבעותיו באצבעו הוא טמא מיד והן טהורין עד שישהא בכדי אכילת פרס פת חטים ולא פת שעורים מיסב ואוכל בליפתן
This is as we learned in a mishna (Nega’im 13:9): With regard to one who enters a leprous house with his clothes resting on his shoulders but who is not wearing them in the normal manner, and his sandals and his rings are in his hands, both he and they, the clothes, sandals, and rings, are rendered ritually impure immediately. If he was dressed in his clothes, and his sandals were on his feet and his rings were on his fingers, he is rendered impure immediately upon entering the house, but they, the clothes, sandals, and rings, remain pure until he remains in the house for the time it takes to eat a half-loaf of bread. This calculation is made with wheat bread and not with barley bread, which takes more time to eat than wheat bread. In addition, the calculation is made with regard to one who is reclining, and eating the bread together with a relish usually consumed with bread, which hastens the eating.
אמר רבא תרוייהו תננהי טומאה בלועה תנינא טהרה בלועה תנינא
§ Rabba stated above that an encapsulated impure item cannot impart impurity and that an item that is ritually pure that is encapsulated within another body cannot be rendered impure. Rava said: Why is this statement necessary? We learn both halakhot in a mishna: We learn about an encapsulated impure item, and we learn about an encapsulated pure item.
טומאה בלועה דתנן בלע טבעת טמאה טובל ואוכל בתרומתו הקיאה טמאה וטמאתו
Rava elaborates: With regard to an encapsulated impure item, the halakha is as we learned (Mikvaot 10:8): If someone swallowed a ring that was impure due to having been in contact with a corpse, he is thereby rendered impure. To render himself pure he immerses and then he may partake of his teruma, despite the fact that the impure ring is still inside him. The reason this is permitted is that since the ring in encapsulated inside the person’s body it cannot impart impurity. If he vomited out this ring it remains impure, as it was not purified by his immersion, and therefore it renders him impure upon its exit from his body.
טהרה בלועה תנינא דתנן בלע טבעת טהורה ונכנס לאהל המת והזה ושנה וטבל והקיאה הרי היא כמה שהיתה
Likewise, we learn the halakha that an encapsulated pure item cannot be rendered impure, as we learn in the same mishna (Mikvaot 10:8): If one swallowed a ritually pure ring and then entered a tent containing a corpse, thereby contracting impurity, and then in order to render him pure someone sprinkled upon him the water that is mixed with the ashes of the red heifer, once on the third day and again on the seventh day as required, and then he immersed, thereby completing the purification process; and then he vomited out the ring, the ring is pure as it always was, i.e., it was not rendered impure from the corpse.
כי קאמר רבה כגון שבלע שתי טבעות אחת טמאה ואחת טהורה דלא מטמיא לה מטמאה לטהורה
The Gemara answers: The cases in the mishna concern the possibility of imparting impurity from the ring to the body within which it is contained and vice versa. But when Rabba was speaking he was referring to imparting impurity from one item to another where both are contained together inside a body, such as where a person swallowed two rings, one impure and one pure, and they came in direct contact with one another. Rabba taught that even in this case the impure ring does not render the pure ring impure.