We are looking at Mishnah 7 in the sixth chapter of Tractate Bava Basra. The first part of the Mishnah comes to discuss the rights of the public regarding a path they have been accustomed to using since time immemorial.
A public path passing through a private field:
The scenario is of a private individual whose private field has a path running through it that the public has used since time immemorial, connecting point A to point B. The owner of the field claims: The path passes through my private property, and I want to take it for myself; in exchange, I will give the public a new path, about five hundred meters to the south, which will also connect those same two points.
The fundamental principle in our Mishnah is that whatever the public has used remains the property of the public, and there is no possibility of taking it back. And from here, the text of the Mishnah:
"Mi shehayesa derech harabim overes besoch sado" - a public passageway, road, path, or street that passes through his private field.
"Netalah venasan lahem min hatzad" - he took the path for himself and offered the public an alternative path: more paved and illuminated, less rugged, and even shortening the distance from point A to point B.
"Mah shenasan nasan" - what he gave to the public becomes their property. The assumption is that the public has already used the new path, and once he handed it over to them, it became part of the public domain.
"Veshelo lo higia" - the part he sought to take for himself does not enter his possession, and he does not have the power to take control of it.
He has no right to take the path from the public, and even if he claims that the alternative path is equally good or even better - his claim is rejected. This is because a person living north of the old path will say: This is not convenient for me, since I am forced to go an extra five hundred amos south to get onto the path, and I want the old path. It turns out that the public is left with their old path, while he gains nothing and loses everything.
Measurements of paths:
From here, the Mishnah moves to a new topic: the measurements of a private path and a public path. This topic returns us to the foundation we dealt with in this chapter and in the previous chapters - one who sells something to his friend, what is included in the sale. Meaning, a person who agreed to pass a private path through his courtyard, whether he received payment for it or not, what is its measurement?
"Derech hayachid arba amos" - about two meters, a width sufficient for the passage of a wagon pulled by oxen. This is the opinion of the Tanna Kamma, and it is the only opinion brought in our Mishnah.
"Acherim" - in a Baraisa brought in the Gemara, it says that we only give two and a half amos for a private path, which is the width required for a donkey with its load to pass. And this is how the halachah is ruled.
"Derech harabim shesh esreh amah" - a very wide measurement, about eight meters, close to thirty feet, like the width of a standard road. This measurement is learned from the fact that this is the measurement of a public domain regarding the laws of carrying on Shabbos.
"Derech hamelech ein lah shiur":
Here, seemingly, the Mishnah deviates for a moment from its topic, and incidental to the discussion of the measurements of paths and the rights of the public, it establishes that a king's path has no measurements. According to most opinions, the meaning is that a king who wishes to travel from point A to point B may pass wherever he wants, even through private property and fences: he tramples the plantings and breaks through the fences to allow himself and his entourage to pass, because the king is the king. There is no minimum measurement here and no maximum measurement.
However, the king does not acquire ownership of the area and is not allowed to confiscate land without reason. The story in the Book of Kings about Achav and Navos is well-known, where the king wanted to take the vineyard and was unable to. A person does not take what is not his, and the king does not have the authority to take things - but he does have the power to pass through them.
"Derech hakever ein lah shiur" - the path to the grave has no measure:
Two explanations are given for this line in the Mishnah:
Some explain that this follows the law of the king: It refers to a funeral procession with a large crowd. Out of respect for the deceased, they are permitted to pass through other people's courtyards and are not required to detour around them. They do not have permission to tear down fences, but they may pass through private property.
Others explain that this refers back to the previous topic - someone who sold his friend a right of way for a burial. Here too it has no fixed measure, meaning there are no set dimensions, and therefore this statement alone does not commit the seller to a specific size.
The ma'amad:
The final part of the Mishnah returns to clearly discuss the sale of a specific item: someone who sells a "ma'amad". A ma'amad is an open area, a kind of plaza where people gather. Different explanations are given regarding what takes place there and what it is used for. Some explain that it is for the seven stops made on the way to the cemetery or on the way back, while others explain that it is for comforting the mourners or listening to the eulogies. In any case, when an open area is needed to accommodate the large crowd attending the funeral, and a person rents a place for this purpose, stating that he needs a space for a ma'amad - how much space does he receive?
"Hama'amad dayanei Tzippori amru: beis arba'as kavin" - the judges of Tzippori ruled that its size is the area required to plant four kavs of grain. In practice, and without going into all the details of the calculation, this refers to an area of fifty by thirty-three amos, which equals one thousand, six hundred and sixty-seven square amos - a substantial area of about twenty-five by sixteen meters. This is the size considered reasonable for holding a ma'amad, and this is the law for someone who rents and pays for a space for a ma'amad in his friend's courtyard for a funeral procession.
To summarize: In this Mishnah we learned that a path used by the public remains theirs, and if the owner of the field takes it and provides an alternative path - "mah shenasan nasan veshelo lo higia" - what he gave, he gave, and his own does not revert to him. We discussed the measurements of the various paths: a private path is four amos according to the Tanna Kamma, and two and a half amos according to Acherim (and this is the halachah), while a public path is sixteen amos. We also learned that the king's path and the path to the grave have no fixed measure, as well as the ruling of the judges of Tzippori that the size of a ma'amad is a beis arba'as kavin.