Umbrellas on Shabbat (Abridged version)

If one circumcised but did not uncover the flesh at the area of the circumcision by folding back the thin membrane beneath the foreskin, it is as if he had not circumcised. GEMARA: Rabbi Avina said that Rabbi Yirmeya bar Abba said that Rav said: When the mishna said most of the corona, they meant the flesh that covers most of the height of the corona, as well as most of its circumference. We learned in the mishna: If the baby was fleshy, the circumcisor corrects the circumcision so that it will not appear uncircumcised. Shmuel said: A child who is encumbered with flesh, one examines him, and as long as when his limb hardens he looks circumcised, one need not circumcise him again. And if not, meaning he does not appear circumcised even then, one must circumcise him again. It was taught in a baraita that Rabban Shimon ben Gamliel says: A child who is encumbered with flesh, one examines him, and as long as when it hardens it does not appear circumcised, one needs to circumcise him again, and if not, one need not circumcise him again. The Gemara asks: What is the practical difference between these two formulations? The Gemara answers: There is a practical difference between them in a case where he appears circumcised but does not appear fully circumcised. According to Shmuel, in order to avoid an additional circumcision, one must appear fully circumcised, and this state is insufficient. According to Rabban Shimon ben Gamliel, only one who appears uncircumcised requires further circumcision; this partial circumcision is adequate. We learned in the mishna: If he circumcised a child but did not uncover the area of the circumcision, it is as if he did not circumcise him. The Sages taught in a Tosefta that one who circumcises a child recites: Who has made us holy through His commandments, and commanded us concerning circumcision. The father of the circumcised child recites: Who has made us holy through His commandments, and commanded us to bring him into the covenant of Abraham, our father. Those standing there recite: Just as he has entered into the covenant, so may he enter into Torah, marriage, and good deeds. And the one who recites the additional blessing says: Who made the beloved one holy from the womb, marked the decree in his flesh, and gave his descendants the seal and the sign of the holy covenant. Therefore, as a reward for this, the living God, our Portion, commanded to deliver the beloved of our flesh from destruction, for the sake of His covenant that He set in our flesh. Blessed are You, Lord, Who establishes the covenant. One who circumcises converts says: Blessed are You, Lord, our God, King of the universe, Who made us holy with His commandments, and commanded us concerning circumcision. And the one who recites the additional blessing recites: Who has made us holy with His commandments, and commanded us to circumcise converts, and to drip from them covenantal blood, as were it not for the blood of the covenant, the heaven and earth would not be sustained, as it is stated: “If My covenant would not be with day and night, the ordinances of heaven and earth I would not have placed” (Jeremiah 33:25), which is interpreted to mean that were it not for the covenant of circumcision that is manifest both day and night, the world would cease to exist. He concludes the blessing with the phrase: Blessed are You, Lord, Who establishes the covenant. When a Jew buys a Canaanite slave, he is obligated to circumcise the slave, as the slave is partially entering the covenant of the Jewish people. One who circumcises slaves recites a blessing similar to those mentioned above: Who made us holy with His commandments, and commanded us to circumcise slaves, and to drip from them covenantal blood, as were it not for the blood of the covenant the heaven and earth would not be sustained, as it is stated: “If My covenant would not be with day and night, the ordinances of heaven and earth I would not have placed” (Jeremiah 33:25). Blessed are You, Lord, Who establishes the covenant. MISHNA: Rabbi Eliezer says: One may suspend and stretch over a base the strainer through which sediment is filtered from wine, on a Festival. And one may place wine through a strainer that was already suspended the day before; however, one may not suspend the strainer on Shabbat. And the Rabbis say: One may not suspend the strainer on a Festival, and one may not place wine for filtering through a suspended strainer on Shabbat; however, one may place wine through a suspended strainer on a Festival. GEMARA: The Gemara raises a difficulty with regard to Rabbi Eliezer’s position: Now, Rabbi Eliezer holds that we may not even add to a temporary tent on Shabbat; could it be that to make a tent is permitted ab initio? Stretching a strainer over a base, which Rabbi Eliezer permits, is comparable to making a tent. The Gemara explains the question: What is this opinion of Rabbi Eliezer’s? As we learned in a mishna: With regard to a window shutter used to cover a skylight, Rabbi Eliezer says: When it is tied to and hanging from the window, i.e., it is not touching the ground, one may shutter the window with it, and if not, one may not shutter the window with it. And the Rabbis say: Both in this case and in that case one may shutter with it. And Rabba bar bar Ḥana said that Rabbi Yoḥanan said: Everyone agrees that one may not construct a temporary tent on a Festival for the first time, and needless to say, one may not do so on Shabbat. The tanna’im disagree only with regard to adding to an existing tent,as Rabbi Eliezer says: One may not add to an existing structure on a Festival, and needless to say, one may not do so on Shabbat. And the Rabbis say: One may add to the temporary structure on Shabbat, and needless to say, one may do so on a Festival. The Gemara answers: Rabbi Eliezer indeed holds that the suspension of a strainer constitutes a prohibited labor. However, Rabbi Eliezer holds in accordance with the opinion of Rabbi Yehuda with regard to actions that facilitate preparation of food on a Festival, as it was taught in a baraita: The only difference between a Festival and Shabbat is with regard to the preparation of food alone. It is permitted to perform labors for the purpose of food preparation on a Festival, but not on Shabbat. Rabbi Yehuda permits even actions that facilitate food preparation on a Festival, e.g., fixing utensils with which food is prepared on the Festival. Similarly, Rabbi Eliezer permits the suspension of a strainer, which would otherwise constitute a prohibited labor, in order to prepare wine for use on the Festival. The Gemara asks: Say that we heard that Rabbi Yehuda permits labors that are otherwise prohibited if they pertain to actions that facilitate food preparation that cannot be performed on the eve of the Festival; however, with regard to actions that facilitate food preparation that can be performed on the eve of the Festival, did you hear that he permits doing so? The Gemara answers: The leniency of Rabbi Eliezer exceeds that of Rabbi Yehuda. Unlike Rabbi Yehuda, Rabbi Eliezer does not distinguish between actions that facilitate food preparation that can and those that cannot be performed on the eve of the Festival. We learned in the mishna: And the Rabbis say: One may not suspend the strainer on a Festival. A dilemma was raised before the Sages: If he suspended a strainer unwittingly, what is the halakha? Rav Yosef said: If he suspended it, he is liable to bring a sin-offering, like anyone who unwittingly performs a labor prohibited by Torah law on Shabbat. Abaye said to him: But if that is so, that an action of that sort constitutes performance of the prohibited labor of building by Torah law, then if one suspended a jug on a peg, is he also liable for building a tent?