MISHNA: The public thoroughfare - [which is] sixteen cubits [wide, as derived] from the wagons used by the [tribal] banners of the desert in Tractate Shabbat [Shabbat 99a:5].

The tanna of the baraita counts up from below to above. If two cubits or three cubits high, he is liable - and if four cubits, he is exempt, since he holds "until means until and not including." All agree that if four cubits he is exempt -- for our tanna, "until" means "until and including"; for the tanna of the baraita, "until" means "until and not including."

Even in a field of thorns - even if the field to which the fire jumped over the fence had been full of thorns, which readily catch fire and allow it to leap, he is exempt.

They [only] taught - that he is exempt.

Only where it blazes high - [as when] fire blazes high from a date palm and goes up.

But when it blazes low - where the wind bends it and forces it sideways, and interrupts the flame and causes it to leap. [Such is] my teacher's explanation. Another explanation: the fire blazes low, and travels, and catches onto grasses and chips on the ground; therefore, even if it crosses through a very wide public domain, he is liable.

In what case is this statement said - that he is exempt if it crossed through a public throughfare.

Shelulit - this will be explained later on. [Bava Kamma 61a:15]

The one who says that it is referring to an actual river, even when there is no water - since it is wide, it is like a public road.

Divide for the purpose of pe’a - [to require the owner] to leave over pe'a from each and every section.

A stream - if there is a field on each side and a deep stream in the middle, one is obligated to leave over pe'a from each and every [field].

A private road - of four cubits[' width].

Sholelin - gathers, as in "from a cluster of eggs" [Beitzah 7a:8]. Another interpretation: in the sense of "spoil and ... booty" [Numbers 31:11] -- something that is gathered.

That distributes spoils to its banks - in that it supplies water to them, and they bring forth fruit.