Rav Ashi said: There was never a need to equate glass vessels and metal vessels. Actually, glass vessels are likened to earthenware vessels in every sense. And that which was difficult for you, that if so, glass vessels, like other earthenware vessels, should not become impure from contact of their outer side with a source of ritual impurity; since in glass vessels its inner side looks like its outer side, the legal status of the outer side was equated with that of the inner side, as there is no visible separation between them.

We learned that Shimon ben Shataḥ instituted the formula of the marriage contract for a woman and decreed impurity upon metal vessels. The Gemara asks: Aren’t metal vessels impure by Torah law, as it is written: “But the gold, and silver, and the bronze, and the iron, and the tin, and the lead. Anything that came in fire, make it pass through fire and it will be pure, but with the water of sprinkling it will be purified and anything that did not come in fire make it pass through water” (Numbers 31:22–23)? The Gemara answers: This ordinance of Shimon ben Shataḥ with regard to the impurity of metal vessels in general was only needed with regard to previous impurity reassumed by metal vessels after they are recast. As Rav Yehuda said that Rav said: There was an incident involving Shimon ben Shataḥ’s sister, Shel Tziyyon the queen, who made a wedding feast for her son. All of her vessels became impure, and she broke them and gave them to the smith, and he welded the broken vessels together and made new vessels. And the Sages said: What she did was ineffective, as all the vessels will reassume their previous impurity.

With regard to the essence of the matter, the Gemara asks: What is the reason that they imposed a decree of previous impurity on metal vessels? The Gemara answers: Due to a fence constructed to maintain the integrity of the water of a purification offering, the Sages touched upon it. In order to purify a vessel that came into contact with a corpse, one is required to have the water of a purification offering sprinkled on the vessel on the third day and the seventh day after it became impure, as it is written: “He should be purified with it on the third day and on the seventh day he will become pure, and if he is not purified with it on the third day and on the seventh day he will not become pure” (Numbers 19:20). This involves a significant inconvenience. If people will prefer to break or damage impure metal vessels in order to purify them more easily, the use of water of a purification offering will become obsolete. As a result, the Sages decreed that metal vessels will remain impure until they undergo the purification process.

The Gemara asks: Granted, according to the one who said that they did not say the decree of previous impurity on metal vessels with regard to all forms of impurity; rather, they only said the decree with regard to the impurity caused by contact with a corpse, it works out well. In the case of impurity caused by contact with a corpse, the Sages issued this decree because its purification process is demanding. It requires immersion and sprinkling of the water of a purification offering on the third and the seventh days. However, with regard to other forms of impurity, whose purification is accomplished by means of immersion alone, a person will not break a vessel in order to avoid immersion. Consequently, there is no need to institute a decree in those cases.

However, according to the one who said that they said the decree of previous impurity in metal vessels with regard to all forms of impurity, which includes those forms of impurity that do not require sprinkling of the water of a purification offering for their purification, what is there to say as a rationale for the decree? Abaye said: Shimon ben Shataḥ instituted a decree due to the concern that perhaps he would not perforate that vessel with a hole large enough to render it ritually pure. To purify a vessel by breaking it, one must make a hole large enough to ensure that the vessel will no longer be able to hold the contents that it was designed to hold. Abaye explained that Shimon ben Shataḥ’s concern was that one who values the vessel will not break it sufficiently to render it ritually pure.

Rava said: It is a decree lest they say that immersion on the same day is sufficient for this vessel to be purified. People will be unaware of the manner in which the metal vessel became pure, and they will assume that its purity was achieved by means of immersion and not by means of breaking. That will lead them to the conclusion that any vessel becomes pure immediately upon immersion, and there is no need to wait for sunset, contrary to Torah law. Therefore, the Sages decreed that repaired vessels retain previous impurity. The Gemara asks: What is the practical difference between the reasons of Abaye and Rava? The Gemara answers: The difference between them is found in a case where he broke the vessel completely. If there was concern that perhaps he will not perforate it sufficiently, there is no longer room for concern. However, if there was concern lest people say that immersion is effective on that day, there remains room for concern.

To this point, several, but not all, of the eighteen decrees were enumerated. The Gemara asks: And what is the other decree? The Gemara answers: As we learned in a mishna in tractate Mikvaot: One who places vessels under the drain pipe in order to collect rainwater, the water collected in the vessels is considered drawn water. This is true both in the case of large vessels which, due to their size, do not become impure, and in the case of small vessels. And even if they were stone vessels and earth vessels and dung vessels, made from dry cattle dung, which are not considered vessels in terms of ritual impurity and do not become impure at all, this ruling applies. The water in the vessels is considered drawn water in all respects. If it leaked from those vessels and flowed into a ritual bath that had not yet reached its full measure, forty se’a, and filled it, the water invalidates the ritual bath. The Gemara adds that this halakha applies both in a case where one places the vessels beneath the drainpipe with premeditated intent to collect the water flowing through it as well as in a case where one forgets the vessels there and they are filled unintentionally; this is the statement of Beit Shammai. And Beit Hillel deem the ritual bath pure, i.e., fit to complete the full measure of the ritual bath, in a case where one forgets the vessels. Rabbi Meir said: They were counted in the attic of Ḥananya ben Ḥizkiya and Beit Shammai outnumbered Beit Hillel. And Rabbi Meir said that Beit Shammai agree with Beit Hillel that in a case where one forgets vessels in the courtyard and they fill with rainwater, the water is pure. Rabbi Yosei said: The dispute still remains in place, and Beit Shammai did not agree with Beit Hillel at all.

Rav Mesharshiya said: The Sages of the school of Rav say: Everyone agrees that if he placed the vessels in the courtyard at the time of the massing of the clouds, a sign that it is about to rain, just before it began to rain, then the water in the vessels is impure, unfit, as he certainly intended that the water fill the vessels. If one placed the vessels at the time of the dispersal of the clouds, and then the clouds massed together, and then rain fell and the vessels filled with the rainwater, everyone agrees that the water is pure. It is fit to fill the ritual bath to its capacity because at the time that he placed the vessels under the drainpipe his intention was not that they fill with rainwater. They only disagreed in a case where he placed them at the time of the massing of the clouds, and the clouds dispersed, and rain did not fall then, and only later the clouds massed again, and rain fell and filled the vessels. In that case, this Sage, Beit Hillel, holds that because the clouds dispersed after he placed the vessels, his thought to fill the vessels with water was negated. The vessels remained in the courtyard due to his forgetfulness, and when they filled afterward it was not his intention that they fill. And this Sage, Beit Shammai, holds that his thought was not negated, as his original intention was ultimately fulfilled despite the delay in its fulfillment.

The Gemara wonders: Indeed, according to Rabbi Meir, another decree was added to the total. However, according to Rabbi Yosei, who said that in this case the dispute still remains in place, the tally of eighteen decrees is lacking. Rav Naḥman bar Yitzḥak said: The decree that the daughters of the Samaritans [kutim] are considered to already have the status of menstruating women from their cradle, their birth, they issued on that day. The halakha is that any female who sees blood of menstruation is impure, regardless of her age, even if she is a day old. The Samaritans did not accept that halakha. Consequently, it is possible that there were girls among them who saw blood of menstruation before their coming-of-age, and the Samaritans ignored their impurity. Therefore, due to this uncertainty, the Sages decreed impurity on all daughters of the Samaritans from birth.

The Gemara asks: And what is the other decree? The Gemara answers that another decree is as we learned a halakhic tradition in a mishna that all movable objects with the width of an ox goad, a long stick for prodding and directing a plowing animal, transmit impurity. If one side of the object was over a corpse and the other side of the object was over vessels, the vessels become impure due to the impurity of a tent over a corpse. Rabbi Tarfon said: