An action undertaken to improve the vessel negates both the status created by an earlier action that supposedly completed the vessel and the status created by the thought not to perform more work on the vessel. In that case the vessel cannot contract ritual impurity until the craftsman has finished working on it. By contrast, a thought to improve the vessel negates neither status created by action nor status created by thought. Reish Lakish finds this difficult for the following reason: Granted, thought does not negate action, as a statement does not come and nullify action. But it should at least offset thought. This halakha indicates that a statement does not nullify a previous statement.

The Gemara answers: Thought in the case of ritual impurity is different, as it is considered like action, and this is in accordance with the opinion of Rav Pappa. As Rav Pappa raises a contradiction: With regard to the halakha that produce must become wet in order for it to contract ritual impurity, the verse states: ''But if water is placed [vekhi yuttan] upon the seed, and any part of a carcass falls upon it, it is impure'' (Leviticus 11:38). The word yuttan is written defective, and is written as if it says ki yitten. Accordingly, this would mean that one must actively place the water on the produce. Yet we read it, based on the tradition as to its correct pronunciation, ''ki yuttan,'' which includes any situation where the produce becomes wet. How so? How can the way the verse is written and the way it is read be reconciled?

Rav Pappa explains that the standard of ''if water is placed [ki yuttan]'' is similar to: If one places [ki yitten]; just as the term places [yitten] indicates that it is satisfactory to the owner for the produce to become wet, as he himself is placing the water, so too, the term ''is placed [yuttan]'' means that it is satisfactory to the owner that the produce becomes wet, despite the fact that he did not place the water himself. This is proof that thought is equivalent to action with regard to ritual impurity, as if one is satisfied with the produce becoming wet it is considered as though he actively placed the water himself. By the same reasoning, thought which renders a vessel susceptible to ritual impurity is powerful enough to require an action to counteract its effect.

The Gemara presents another version of the discussion: Rav Zevid taught this dispute with regard to this halakha: And similarly, in a case where she gave permission to her agent to accept betrothal for her and she subsequently went and accepted betrothal herself from someone else, if her betrothal came first, her betrothal is a valid betrothal, but if the betrothal of her agent came first, her betrothal is not a betrothal.

The Sages discuss this halakha: If she did not accept betrothal herself and retracted her appointment of the agent, what is the halakha? Rabbi Yoḥanan says: She can retract her appointment; and Reish Lakish says: She cannot retract her appointment. The Gemara clarifies their respective opinions. Rabbi Yoḥanan said: She can retract her appointment, as a statement comes and nullifies a previous statement, by which she appointed the agent. Reish Lakish said: She cannot retract her appointment, as a statement does not come and nullify a previous statement.

Rabbi Yoḥanan raised an objection to Reish Lakish from the aforementioned mishna (Terumot 3:4) with regard to one who appointed an agent to separate teruma on his behalf and subsequently canceled the agency: If he canceled the appointment before the agent separated teruma, his teruma is not teruma. This shows that a statement nullifies a previous statement. Rava says: With what are we dealing here? With a case where the homeowner preceded the agent and separated teruma from his heap himself, which is an action, and an action certainly nullifies a statement.

Reish Lakish raised an objection to Rabbi Yoḥanan: All vessels descend into their state of contracting ritual impurity by means of thought. But they ascend from their state of ritual impurity only by means of a change resulting from an action. An action undertaken to improve the vessel negates both the status created by an earlier action that supposedly completed the vessel and the status created by the thought not to perform more work on the vessel. By contrast, a thought to improve the vessel negates neither status created by action nor status created by thought. Reish Lakish explains his objection: Granted, thought does not negate action, as a statement does not come and nullify action. But it should at least offset thought.

Rabbi Yoḥanan said to Reish Lakish: Thought in the case of ritual impurity is different, as it is considered like action, and this is in accordance with the opinion of Rav Pappa. As Rav Pappa raises a contradiction: The word yuttan is written defective, and is written as if it says ki yitten. Yet we read it ''ki yuttan.'' How so? The standard of ''if water is placed [ki yuttan]'' is similar to: If one places [ki yitten]; just as the term places [yitten] indicates that it is satisfactory to the owner for the produce to become wet, as he himself is placing the water, so too, the term ''is placed [yuttan]'' means that it is satisfactory to the owner that the produce becomes wet, despite the fact that he did not place the water himself.

Rabbi Yoḥanan raised an objection to Reish Lakish: With regard to one who sends a bill of divorce to his wife, and later the husband encountered the agent or sent another agent after him and in this manner said to him: The bill of divorce that I gave you is nullified, it is thereby nullified. This indicates that the appointment of an agent can be nullified even by a statement. The Gemara concludes: The refutation of the opinion of Reish Lakish is in fact a conclusive refutation.

The Gemara adds: And the halakha is in accordance with the opinion of Rabbi Yoḥanan, and this is even according to the first version of their dispute, with regard to a woman who retracts from her betrothal after accepting the money for it. And even though there is room to say that giving money to a woman for betrothal is different, as it is considered like an action, even so, a statement comes and nullifies a previous statement with regard to her consent to the betrothal, provided that the betrothal has yet to take effect.

The Gemara asks: The halakha recorded here is difficult with regard to the halakha recorded elsewhere. You said that the halakha is in accordance with the opinion of Rabbi Yoḥanan, and yet we maintain that the halakha is in accordance with the opinion of Rav Naḥman. As a dilemma was raised before the Sages: What is the halakha in the case of a bill of divorce sent by an agent that the husband nullified before it was received by his wife? Can the husband return and divorce his wife with the very same bill of divorce?

Rav Naḥman says: He can return and divorce her with it, and Rav Sheshet says: He cannot return and divorce her with it. And we maintain that the halakha is in accordance with the opinion of Rav Naḥman in this case. By contrast, according to the ruling of Rabbi Yoḥanan, since the husband has nullified the bill of divorce it should no longer be valid. The Gemara answers: This is not difficult, as, although the husband has nullified the agent from his status as an agent, he has not nullified the bill of divorce itself from its status as a bill of divorce.

§ The mishna teaches that if a man betroths a woman and stipulates that the betrothal will take effect in thirty days’ time and another man betroths her within that period, she is betrothed to the second man. Rav says: She is betrothed to the second forever, i.e., the betrothal is fully effective, and Shmuel says: She is betrothed to the second until the thirty days pass. After thirty days have passed, the betrothal of the second lapses, and the earlier betrothal of the first man is completed.

Rav Ḥisda sat and found this difficult: By what means is the betrothal of the second man abrogated? When the second betrothal took effect, the first betrothal was not yet in effect. Why, then, is the second betrothal abrogated? Rav Yosef said to him: The Master teaches this dispute with regard to the first clause of the mishna, and therefore he finds it difficult, whereas Rav Yehuda teaches it with regard to the latter clause of the mishna, and consequently he does not find it difficult.

Rav Yehuda’s version of the dispute is as follows: The mishna teaches that if the first man says to her: You are hereby betrothed to me from now and after thirty days, and another man betrothed her within those thirty days, there is uncertainty whether she is betrothed or whether she is not betrothed. Rav says: This means that there is uncertainty whether she is betrothed or whether she is not betrothed forever, and her only option is to receive a bill of divorce from both men. And Shmuel says: There is uncertainty whether she is betrothed or whether she is not betrothed only until thirty days have elapsed, whereas after thirty days the betrothal of the second is abrogated, and the betrothal of the first is completed.

The Gemara explains their respective opinions: Rav is uncertain what the first man meant. Is it a condition, i.e., the man is saying: If I do not change my mind within thirty days, you are betrothed to me from now, or is it a retraction, that is, he immediately retracted after he said: From now, in favor of a betrothal that will take effect only after thirty days have elapsed. This uncertainty remains even after the end of the thirty days. It is obvious to Shmuel that it is a condition. Consequently, the uncertainty whether or not she is betrothed to the second man applies during the thirty-day period, as the first man might yet change his mind. After the completion of thirty days, the betrothal from the first man retroactively takes effect from the moment he gave it, and therefore the betrothal of the second man is abrogated.

The Gemara comments: And Rav and Shmuel disagree in the dispute between these tanna’im. As it is taught in a baraita: If one says to his wife upon giving her a bill of divorce that it should take effect: From today and after my death, there is uncertainty whether it is a valid bill of divorce or whether it is not a valid bill of divorce. This is the statement of the Rabbis. The Rabbis are uncertain whether he meant that the bill of divorce should take effect retroactively from that moment, in which case it is valid; or whether he changed his mind and meant for it to take effect only after his death, which would mean that it is not a valid bill of divorce. Rabbi Yehuda HaNasi says: A document like this is a valid bill of divorce. The husband meant his statement as a condition that the bill of divorce should, after his death, take effect retroactively from now, and therefore it is a valid bill of divorce.

The Gemara asks: And let Rav, instead of explaining his own opinion, say that the halakha is in accordance with the opinion of the Rabbis, and let Shmuel say that the halakha is in accordance with the opinion of Rabbi Yehuda HaNasi. The Gemara answers: It is necessary for Rav and Shmuel to state their disagreement explicitly. As had Rav merely said that the halakha is in accordance with the opinion of the Rabbis, I would say: There, in the case of a bill of divorce, when he comes to distance her from himself, one can say that he has changed his mind with regard to the divorce. But here, in the case of betrothal, when he comes to draw her near, you might say that Rav concedes to Shmuel that it is certainly a condition, as he wants to betroth her as soon as possible.

And conversely, had Shmuel said only that the halakha is in accordance with the opinion of Rabbi Yehuda HaNasi, I would say: It is in that case there that Rabbi Yehuda HaNasi said it is a valid bill of divorce, as there is no bill of divorce after death, and therefore it is unlikely that he changed his mind and attempted to give a bill of divorce that will take effect only after the death of the husband. But here, where there is the possibility of betrothal after thirty days, and he might well have intended to retract the betrothal, you might say that Shmuel concedes to Rav. Consequently, it was necessary to state the dispute between Rav and Shmuel concerning betrothal in explicit terms.

Abaye said: And according to the reasoning of Rav, if one man came and said the following ambiguous statement to her: You are hereby betrothed to me from now and after thirty days. And another man came during these thirty days and said to her: You are hereby betrothed to me from now and after twenty days,