Ostensibly, the two clauses of the baraita are difficult, as they contradict each other, since the first clause states that slaughter with a blade that is attached is valid and the latter clause states that slaughter is not valid. Rather, must one not conclude from it that there is a difference between a case where the blade was attached from the outset and a case where the blade was detached and ultimately he reattached it? The Gemara affirms: Indeed, learn from it.

§ The Master said: In the case of one who slaughters with a mechanism of a wheel with a knife attached to it, his slaughter is valid. The Gemara asks: But isn’t it taught in a baraita that his slaughter is not valid? The Gemara answers: This contradiction is not difficult. This baraita, which rules that the slaughter is valid, is in a case where the knife was attached to a potter’s wheel, whose movement is generated by the potter pressing on a pedal. Since the slaughter was performed by the force of the person’s actions, the slaughter is valid. That baraita, which rules that the slaughter is not valid, is in a case where the knife was attached to a waterwheel. Since the slaughter was not performed by the force of the person’s actions, the slaughter is not valid.

And if you wish, say instead: The rulings of both this baraita and that baraita are in a case where the knife was attached to a waterwheel, and the contradiction is not difficult. This baraita, which rules that the slaughter is valid, is in a case where the movement of the slaughter was generated by primary force, as the person releases the water that turns the wheel, and on that initial turn of the wheel the knife slaughters the animal. That baraita, which rules that the slaughter is not valid, is in a case where the slaughter was generated by secondary force, as the knife slaughters the animal on the second turn of the wheel.

And this is like that which Rav Pappa says: In the case of a certain person who bound another and diverted a flow [bidka] of water upon him and he died, the one who diverted the water is liable for his murder. What is the reason? It is because those were his arrows that were effective in his murder. And this matter applies in a case where he killed the other person by primary force, as the person was proximate to him and was directly drowned by the water. But if the person was further away and was killed by secondary force after the water flowed on its own, it is not by his direct action; rather, it is merely an indirect action, and he is exempt.

§ Rav sat behind Rabbi Ḥiyya, and Rabbi Ḥiyya sat before Rabbi Yehuda HaNasi, and Rabbi Yehuda HaNasi sat and said: From where is it derived that slaughter is performed specifically with a blade that is detached? It is derived from a verse, as it is stated: “And Abraham stretched forth his hand and took the knife to slaughter his son” (Genesis 22:10). Rav said to Rabbi Ḥiyya: What is he saying? Rabbi Ḥiyya said to Rav: He is saying an incorrect reason, comparable to the letter vav that is written on the rough surface of a tree trunk [a’ufta]. The Gemara asks: But didn’t Rabbi Yehuda HaNasi say a verse as proof for his statement? The Gemara answers: The verse teaches us the diligence of Abraham, who had a knife prepared to slaughter Isaac. It does not teach any halakha concerning ritual slaughter.

§ Apropos the issue of slaughter with a detached blade, Rava said: It is obvious to me that concerning an item that was detached and ultimately one attached it, with regard to the matter of idol worship its halakhic status is that of a detached item, as the Master says: One who bows to his house has rendered it forbidden as an object of idol worship. And if it enters your mind to say that its halakhic status is that of an attached item, it is written with regard to idolatry: “Their gods, upon the high mountains” (Deuteronomy 12:2), from which it is derived: But the mountains are not their gods, as items attached to the ground are never rendered forbidden as objects of idol worship. The halakhic status of a house built from stones that were detached is that of a detached item.

With regard to the matter of rendering seeds susceptible to ritual impurity, there is a dispute between tanna’im, as we learned in a mishna (Makhshirin 4:3): In the case of one who places a bowl on the wall while it is raining so that the bowl will be rinsed with the rainwater, if the water from the bowl then falls onto produce, that is under the rubric of the verse: “But when water is placed upon the seed” (Leviticus 11:38). The water has the halakhic status of a liquid that he poured of his own volition on fruit and seeds. Consequently, it renders them susceptible to ritual impurity. But if he placed the bowl there so that the wall will not be damaged, it is not under the rubric of the verse “but when water is placed upon the seed.” Since he had no intent to use the water, it is not considered to have entered the bowl of his own volition, and it does not render produce susceptible to impurity.

This mishna itself is difficult, as the inferences from the first clause and the latter clause are contradictory. In the first clause you said: In the case of one who places a bowl on the wall so that the bowl will be rinsed with the rainwater, that is under the rubric of the verse “but when water is placed upon the seed,” and the water renders produce susceptible to impurity. By inference, if he placed the bowl so that the wall will be rinsed by means of the bowl, that is not under the rubric of the verse “but when water is placed upon the seed.” That water would not render produce susceptible to impurity, because the intent was for the water to rinse the wall, which is an item attached to the ground.

And then the mishna teaches in the latter clause: If he placed the bowl so that the wall will not be damaged, it is not under the rubric of the verse: “But when water is placed upon the seed.” By inference, if he placed the bowl so that the wall will be rinsed, that is under the rubric of the verse: “But when water is placed upon the seed,” as a wall has the status of a detached item, since it was built from stones that were detached.

Rabbi Elazar said: This mishna is disjointed; the tanna who taught this first clause did not teach that second clause. There is a tannaitic dispute whether the status of a wall that is built from detached stones is that of an attached item or a detached item. Rav Pappa said: The entire mishna is the opinion of one tanna: This first clause is in the case of the wall of a cave, which is attached from the outset; that latter clause is in the case of the wall of a building, which is built from stones that were detached from the ground.

And this is what the mishna is saying: In the case of one who places a bowl on the wall so that the bowl will be rinsed with the rainwater, that is under the rubric of the verse “but when water is placed upon the seed,” and the water renders produce susceptible to impurity. By inference, if he placed the bowl so that the wall will be rinsed by means of the bowl, that is not under the rubric of the verse “but when water is placed upon the seed.”

In what case is this statement said? It is said in the case of the wall of a cave, which was always attached to the ground. But in the case of the wall of a building, whose stones were detached and subsequently reattached, if he places the bowl so that the wall will not be damaged, that is when it is not under the rubric of the verse “but when water is placed upon the seed.” But if he places the bowl so that the wall will be rinsed, that is under the rubric of the verse “but when water is placed upon the seed.”

Rava raises a dilemma: