We are starting right at the beginning, in the third line. We previously discussed a disagreement concerning someone who was on a boat at the beginning of Shabbat, when the boat broke loose and traveled beyond the Sabbath boundary. The question was whether he was permitted to walk throughout the entire boat.
The Gemara now discusses that case. We are speaking about a boat that came to a stop. There was a disagreement between Rabban Gamliel and Rav Huna regarding a moving boat. When the boat is moving, everyone agrees that a person may walk throughout the entire boat. The simple reason is that with every movement of the boat, the person is continually receiving another four cubits. When the Sabbath boundary ends, a person always has at least four cubits available, and as the boat moves, those four cubits are continually renewed. The disagreement applies when the boat stops.
The Gemara begins bringing proofs for this. Rav Nachman bar Yitzchak said that when the boat is moving, everyone agrees that it is permitted to walk throughout the entire boat. From where do we know this?
There was an incident involving two rabbis who came from Italy. Their boat was in the harbor when Shabbat began, and afterward the boat started moving on Shabbat and traveled beyond the boundary. The two rabbis walked throughout the boat. This shows that when the boat was moving, there was no disagreement that they could walk throughout it.
The reason Rabban Gamliel and Rabbi Yehoshua were stringent was that they were concerned the boat might stop. If it stopped, the person would no longer have the entire boat available to him; he would have only four cubits. But if you say that the disagreement applies even while the boat is moving, then it would be prohibited to walk throughout the boat even while it was moving. Rav Ashi therefore brings another proof.
Rav Ashi says that the wording of the Mishnah is precise. It mentions a boat in parallel with a pen and a courtyard. Just as a pen and a courtyard are stationary, the boat in the Mishnah must also be stationary. This is another indication that the disagreement applies when the boat has stopped. If the boat is moving, everyone agrees that the entire boat may be traversed.
Rabbah bar bar Chanah said in the name of Rabbi Yochanan that the law regarding a boat follows Rabban Gamliel. The Gemara asks: Does this imply that Rabban Gamliel disagrees with the other view? If no one disagreed with Rabban Gamliel, there would be no need to say that the law follows him. The Mishnah merely says that Rabban Gamliel was stringent; it does not explicitly state that anyone disagreed with him.
The Gemara answers that Rabban Gamliel’s stringency may have been an additional personal stringency rather than the basic law. In principle, he too agreed that while the boat was moving, a person could walk throughout it. He was stringent because he was concerned that the boat might stop. If it stopped, there would be a problem, so his conduct reflected an added stringency rather than the essential law.
Perhaps this was the entire discussion of the rabbis who were on the boat on Shabbat: whether they could move throughout the boat or not. This would explain why they were concerned. However, that does not necessarily prove that there was a disagreement about a moving boat itself. The question may have been what would happen if the boat stopped.
Another passage discusses people who were taken by non-Jews on Shabbat and placed in a pen or a courtyard. In that case, the ruling depends on the fact that a pen and a courtyard are stationary. This is another indication that the boat under discussion is a stationary boat. The disagreement is when the boat is fixed in place; when it is moving, everyone agrees that one may walk throughout it.
We now come to a basic question in our discussion: Is there a Sabbath boundary above ten handbreadths? We encountered this question previously. Our boat is in deep water, but the issue is that a Sabbath boundary is generally measured from the ground—the place where a person is walking. What happens when a person is elevated? If the water is deep and he is standing on a boat, is there a Sabbath boundary above ten handbreadths?
Consider a pillar that is ten handbreadths high and four handbreadths wide. It is within the boundary, but it extends outward beyond the boundary. There is no question that a person may walk on that pillar beyond the boundary. The reason is that the pillar is considered an extension of the ground. It is similar to a mound that people can walk over in the public domain. Therefore, even though it is higher than ten handbreadths, it is considered part of the public domain and part of the person’s Sabbath boundary.
The question is when the pillar is ten handbreadths high but less than four handbreadths wide. Since it is narrow and difficult to walk on, is it still considered part of the person’s Sabbath boundary?
Another possibility involves someone traveling through the air by means of a magical name. In that case, he is using sacred names and moving through the air. Is there a Sabbath boundary in the heavens? A third formulation of the question concerns a boat in deep water: Is there a Sabbath boundary above ten handbreadths in the case of a boat?
Thus, there are three examples of being above ten handbreadths: a pillar that is not four handbreadths wide, someone traveling through the air by means of sacred names, and a boat in deep water. Is there a Sabbath boundary in such cases?
The Gemara brings a proof. A group of people came from overseas, and their boat arrived at the harbor. If you say that there is a Sabbath boundary above ten handbreadths, that would explain why they were stringent concerning the boundary. The assumption is that the boat was in deep water, and nevertheless they were stringent regarding the Sabbath boundary. If there is no Sabbath boundary above ten handbreadths, however, why were they stringent?
The Gemara answers that the water may have been shallow. The boat may have been traveling in a low area, so there was in fact a Sabbath boundary on the ground beneath it. Therefore, no proof can be brought from that incident that there is a Sabbath boundary above ten handbreadths.
The Gemara brings another proof. On one occasion, people arrived at the harbor only after sunset, on Shabbat. Since their Sabbath boundary was established according to the location of the boat when Shabbat began, they tried to determine where the boat had been at that time in order to establish the boundary. If there is a Sabbath boundary above ten handbreadths, this makes sense. But if there is no Sabbath boundary above ten handbreadths, why did they need to determine their location?
The same answer is given: the boat may have been in shallow water. The question could therefore be answered by the location of the ground beneath the boat. This incident does not prove that there is a Sabbath boundary above ten handbreadths.
The Gemara brings another proof. Seven teachings were delivered on Shabbat morning in the academy of Rav Chisda in Sura. After Shabbat, as the sun was setting, the same seven teachings were delivered in the academy of Rabbah in Pumbedita, which was outside the Sabbath boundary of Sura.
Who delivered these teachings? It must have been Elijah the Prophet. How could he travel from Sura to Pumbedita and teach in both places? A human student could not travel beyond the Sabbath boundary on Shabbat. It must therefore have been Elijah the Prophet, who traveled through the air. This would prove that there is a Sabbath boundary above ten handbreadths: even Elijah the Prophet could not travel beyond it.
The Gemara rejects the proof. Perhaps it was Joseph the demon who delivered the teachings in both places. A demon is not bound by the laws of Shabbat in the same way. So although Joseph may have had a good name, he was not necessarily particularly observant. This is not a proof regarding the Sabbath boundary above ten handbreadths.
The Gemara brings another case. A person made a vow that he would become a Nazirite on the day the Messiah arrives. Since the Messiah could arrive every day, he must be careful every day not to drink wine. Nevertheless, he is permitted to drink wine on Shabbat and on festivals, because the Messiah will certainly not arrive on those days. On the other days of the week, however, he may not drink wine.
Why is he permitted to drink wine on Shabbat and festivals? If there is a Sabbath boundary above ten handbreadths, perhaps the Messiah cannot arrive on Shabbat or a festival because he would have to travel beyond the boundary. But if there is no Sabbath boundary above ten handbreadths, he could travel through the air. He should therefore be required to refrain from wine on Shabbat and festivals as well.
The Gemara responds that this is not necessarily a proof. We know that Elijah the Prophet is supposed to precede the Messiah and announce his arrival. Once we know that Elijah the Prophet did not arrive on Friday, we know that the Messiah will not arrive on Shabbat. That is why the man may drink wine on Shabbat.
But this creates a difficulty. If Elijah the Prophet did not arrive on Friday, the same reasoning should apply during the week. If he did not arrive on the previous day, why should the person be prohibited from drinking wine today? Perhaps Elijah the Prophet came to the great court in Jerusalem, but we did not hear about it. If that is possible, then the same uncertainty should exist on Shabbat. The person should have to refrain from wine on Shabbat as well.
The Gemara explains that we have a tradition that Elijah the Prophet does not come on the eve of Shabbat or on the eve of a festival, because of the inconvenience it would cause the Jewish people. People would have to leave their preparations and go out to greet him. They need to shop and prepare food for Shabbat and the festival, so Elijah does not come at those times.
This is also why certain communities do not recite a prayer asking for redemption on Friday. Since the Messiah cannot arrive on Friday, there is no reason to make that request on that day. The permission to drink wine on Shabbat is therefore based not on the rules of Sabbath boundaries, but on the tradition that Elijah does not come on the eve of Shabbat or a festival.
However, the Gemara then asks: Why is the man not permitted to drink wine on Friday itself? If Elijah does not come on Friday because of the inconvenience, perhaps the Messiah can come on Friday. The Messiah would not be prevented by that concern, because as soon as he arrives, the entire Jewish people become his servants. He can give them instructions, and they will carry them out. Therefore, the man is permitted to drink wine on Friday, because the Messiah may arrive that day.
But this still does not prove anything about a Sabbath boundary above ten handbreadths. The Messiah may arrive on Friday, while Elijah does not arrive on Friday. Since Elijah is supposed to precede him, the Messiah cannot arrive on Shabbat, but that is due to the tradition regarding Elijah, not necessarily because of a Sabbath boundary.
The Gemara then returns to the Nazirite. Why is he prohibited from drinking wine on Sunday? Perhaps Elijah came on Shabbat, traveling above ten handbreadths, and the Messiah could therefore arrive on Sunday. If there is no Sabbath boundary above ten handbreadths, Sunday should be a possible day for the Messiah’s arrival, and the man should be prohibited from drinking wine.
The Gemara answers that the teaching itself was uncertain regarding whether there is a Sabbath boundary above ten handbreadths. Since it was uncertain whether Elijah could arrive on Shabbat, Sunday was also uncertain. The man was stringent and refrained from wine on Sunday as well. This does not provide a proof either way. Perhaps Elijah could come on Shabbat, and perhaps he could not; because of that uncertainty, the man acted stringently.
The Gemara then returns to the wording of the vow. On what day did this person make his vow to become a Nazirite? If he made the vow during the week, then he would already be a Nazirite from that day, because perhaps Elijah had come the previous day and the Messiah would arrive today. How could Shabbat exempt him from his Nazirite status? Once he made the vow, he became a Nazirite, at least for the minimum period of Nazirite observance. Therefore, the statement that he may drink wine on Shabbat cannot apply if he made the vow during the week.
It must be that he made the vow on Shabbat or on a festival. On that day he may drink wine, because it is known that the Messiah will not arrive on the preceding day in a way that would create this concern. After that, however, he must be careful. If he makes the vow during the week, he is already a Nazirite, and the Shabbat exemptions do not remove his Nazirite status.
Let us return to the incident in the Mishnah in which people arrived at the harbor close to Shabbat. The Mishnah says that on one occasion they arrived at the harbor as it was becoming dark. They asked Rabban Gamliel whether they could disembark. He told them that they could, because he had been watching and knew that they had been within the Sabbath boundary before Shabbat began.
The question was how he knew this. Perhaps they had been outside the boundary when Shabbat began, in which case they could not disembark. Rabban Gamliel explained that he had watched their position and knew that they had entered within the boundary before dark.
The Talmud teaches that Rabban Gamliel had a viewing tube. Using it, he could see two thousand cubits on dry land. He could also use it to measure the distance across the water. He therefore knew how far they were from the harbor and could determine that they had entered the Sabbath boundary before Shabbat began.
The question arises: How could this device measure a distance across a valley? First, one measures the device on dry land. One determines how far one can see through it—perhaps one thousand cubits—and marks that measurement. Once one knows the distance represented by the view through the device, one can stand at the edge of the valley and look down. One walks backward until the bottom of the valley is no longer visible. The distance one walked backward, subtracted from the known measurement, allows one to determine the depth of the valley.
In other words, first determine the distance that can be seen on level ground. Then look down into the valley and walk backward until the bottom can no longer be seen. The difference between the original measurement and the distance walked backward indicates the depth of the valley. This works only when the slope and the conditions allow the bottom to be seen in that way.
The same principle can be used to measure the height of a tree. Measure one’s own height and the length of one’s shadow. Then measure the length of the tree’s shadow. Based on the ratio between one’s height and one’s shadow, one can calculate the height of the tree. The ratio between the tree and its shadow will correspond to the ratio between one’s own height and one’s shadow.
There is also a discussion about constructing a tomb or mound so that wild animals will not enter its shade. Animals may seek shade near a tomb because the shade is cool. They may also smell the body and dig in the earth. Therefore, the structure should be constructed so that it does not provide a comfortable area of shade for the animals.
The method is to place a pole in the ground during the hottest part of the day and observe where its shadow falls. One constructs the mound with a slope so that the shadow will not remain in one place. The structure is made slanted on both sides. Eventually a shadow will fall there, but by that time the sun will no longer be so strong, and the animals will not remain in that spot for long. By the time they reach the shade, the period of intense heat will already have passed.
This is another example of how measurements were made. One can place a pole in the ground, observe where its shadow falls, and construct the structure so that the shadow moves away from the area. During the time when the sun is strongest, the shade is especially attractive to animals, so the structure is designed to prevent them from settling there.
We now return to the case of Rabbi Nechemiah. He was deeply involved in his learning and became lost while walking. As a result, he went outside the Sabbath boundary. The people around him told him that he was allowed to walk only four cubits. They then formed a human partition around him so that he could enter the area enclosed by them and return to his original boundary.
The rule is that if a person leaves his Sabbath boundary, he may walk only four cubits. However, if people surround him and form a partition, he may enter the area enclosed by that partition. Once inside, he may walk throughout the enclosed area. The people had to be able to reach his location in order to form the partition around him.
There was a question about whether the people could create such a human partition on Shabbat. The partition was formed on Shabbat, and it was not a permanent structure. Could they nevertheless surround him and allow him to return?
Rav Nachman was sitting behind Rabbah, while Rabbah was sitting before Rav Nachman. Rav Nachman asked what Rav Chisda’s uncertainty had been in the case of Rabbi Nechemiah. If there were enough people to reach Rabbi Nechemiah and form a partition around him, what was the question? Once they formed the partition, he would have the entire enclosed area available to him.
Perhaps the uncertainty was whether this rule applies when the person left the boundary voluntarily. In the case of the boat, the person had not left the boundary on his own; he had been carried out. Perhaps a partition helps only when someone was taken out against his will and placed in an enclosed area. Rabbi Nechemiah, however, had gone outside the boundary while absorbed in his learning. Would a partition still help him?
Alternatively, perhaps there were not enough people to reach him directly. The question may have been whether a human partition could be formed when there was a gap of two cubits between the people and Rabbi Nechemiah. If the law permits a person who is within two cubits of his boundary to return, perhaps they could make use of those two cubits and bring him back into the permitted area.
Later, we learn about someone who went only two cubits beyond the Sabbath boundary. In such a case, he may return, because the two cubits are treated as an additional allowance. The question in Rabbi Nechemiah’s case may have been whether the people could form a partition that reached to within two cubits of him and then allow him to use those remaining two cubits.
Rav Nachman told them to form a partition and bring him inside. The wording “bring him inside” may be precise. Perhaps it meant that they should form a partition up to the point where they could reach him, and he would then use the remaining two cubits to enter. This indicates that the uncertainty concerned whether the two-cubit allowance could be combined with the human partition.
The people therefore formed a circle around Rabbi Nechemiah. He could walk to the edge of the circle, and from there he still had two cubits remaining before reaching the area he wanted to enter. Rav Nachman told him to enter using those two cubits. That was the issue under discussion.
A related question was posed concerning a booth whose wall fell down on a festival. Could people or animals be used to form a temporary wall? Could one raise a bed, place a sheet over it, and use it as a wall? The question is whether a temporary wall may be constructed on Shabbat or a festival.
One passage says that a person, an animal, or some other object cannot be used to complete the wall. Another passage appears to permit using a person as a wall. The Gemara resolves the contradiction by distinguishing between adding to an existing structure and creating a new structure.
There is a similar discussion regarding a window shutter. If the shutter is already attached to the wall and merely hangs there, one may close it, because it is already part of the wall. If it is not attached and one places it there to close the opening, that resembles building and is prohibited by rabbinic decree.
The same distinction applies to a booth. One source that permits a temporary wall is speaking about adding to an existing structure. The booth already has the necessary structure, and one is merely adding to it. The source that prohibits it is speaking about creating a new temporary shelter or a new wall that completes the structure.
At first, the Gemara considers whether the distinction follows the view of Rabbi Meir or the view of the Rabbis. Rabbi Meir says that an animal cannot serve as a wall. However, perhaps he objected only to an animal and not to a human being or a permanent wall. In addition, even if one permits an animal as a wall, one must still ask whether the wall is creating a new shelter or merely adding to an existing one.
The Gemara therefore explains that both sources may follow the view of the Rabbis. The contradiction concerning a wall can be resolved by distinguishing between a third wall and a fourth wall. Two walls do not yet create a complete shelter. When one adds a third wall, that wall completes the structure and creates the shelter. Therefore, using a person or an animal to create the third wall is prohibited. If the shelter already exists and one is merely adding a fourth wall, that may be permitted.
How do we know that this is the distinction? The wording of the source speaks of a wall that fell. That suggests a wall that was intended to serve as one of the main walls and whose restoration would complete the structure. If the language had simply referred to an additional wall, it could have been speaking about adding to a structure that was already complete.
There is still a difficulty regarding the human being. One source says that a person may not be used as the wall, while another says that a person may be used to permit eating and sleeping in the booth. It sounds as though the person is being used to make the booth valid, which would mean that he is serving as the third wall, not merely as an additional wall.
The Gemara answers that the distinction is whether the person knows what he is doing. If a person is told merely to stand in a particular place, without being told that he is serving as a wall, he may be used in that manner. Since he does not know that he is helping to create the structure, he is not considered to be intentionally constructing a wall. If he knows that he is being placed there to serve as the wall, however, it is prohibited.
This explains the story involving the people who surrounded Rabbi Nechemiah. They were told simply to form a circle around him. They were not necessarily told that they were creating a legal partition. Because they did not know the halachic function of what they were doing, their arrangement could serve as the partition.
There is another story involving members of a wedding party. They needed to transport water into a private domain, so they formed a human partition around the water. In that way, they were able to bring it into the private domain. Rav Shmuel struck them and rebuked them. He said that if the ruling had been stated only in a case where the participants did not know what they were doing, then they could not deliberately organize themselves as a partition.
Another case involved leather flasks or containers in the street. Rabbah was coming from the study hall with an entourage around him. The attendants wanted to bring him into a private domain by surrounding him with a human partition. This time, however, the attendants knew exactly what they were doing. They intentionally formed the partition in order to permit Rabbah to enter.
The question was whether people who knowingly form a partition may be used for that purpose. In the earlier case, the people did not know that they were forming a partition. Here, the attendants were aware of the plan. The distinction is therefore whether the people are intentionally serving as a partition or are merely standing in a particular arrangement without knowing its halachic purpose.
A similar discussion concerns bringing straw or other material into a private domain on Shabbat. People or animals may sometimes be arranged as a temporary barrier, but the same questions remain: Is the barrier being used to create a new structure, or is it merely adding to an existing one? Do the people or animals know that they are serving as a wall? These distinctions determine whether the arrangement is permitted.