Whenever there is a covering that is a handbreadth by a handbreadth that is a handbreadth high, it is considered an ohel, as we explained. It intervenes in the face of ritual impurity and conveys ritual impurity whether it was made as a shelter or came into being as a matter of course. Even if it was brought into being without human activity, it conveys ritual impurity and intervenes in the face of it. What is implied? If there was a cavern that was hollowed out by water or crawling animals or even if the earth itself cratered or one gathered stone and beams and created a covered space of a handbreadth, it is considered as an ohel and it conveys ritual impurity and intervenes in the face of it.
When does the above apply? When the ohel was strong and sturdy. A unstable ohel, by contrast, does not convey ritual impurity, nor does it intervene in the face of ritual impurity according to Scriptural Law. According to Rabbinic Law, by contrast, it conveys ritual impurity, but does not intervene in the face of it. What is implied? When branches of trees that hang over the earth which are called sichachot and stones which project outward from a wall that hang over the earth and are called peraot are sturdy enough to carry an average ceiling and remain standing, they convey impurity and intervene in the face of it according to Scriptural Law. If they are not sturdy enough to carry an average ceiling and would fall, they convey impurity according to Rabbinic decree and do not intervene in the face of it. Similar laws apply in all analogous situations.
These substances convey ritual impurity and intervene in the face of it: oversized wooden vessels, keilim made from stone, animal turds, or earth that are oversized, simple leather keilim, a curtain, a sheet, or a reed mat that are made like tents, animals or beasts, whether kosher or non-kosher, provided the head of one is placed between the legs of another and they are flush against each other, a bird that rests, one who digs out a place for a child in a grainheap to save him from the sun, and food that was not made ready to be susceptible to ritual impurity so that it would not become impure. When vegetables continue to grow in the summer and the winter, they are considered like trees and convey ritual impurity and intervene in the face of it. Among those in this category are: mint, bindweed, wild gourd, and Greek squash. Similarly, all of the following - branches of trees that hang over the earth, stones which project outward from a wall, projections, balconies, dovecotes, the clefts of stones, stones that stick out of a wall, the arches of a wall, and stony precipices - convey ritual impurity and intervene in the face of it.
The following convey ritual impurity, but do not intervene in the face of it: a human being, wooden vessels that are not oversized, because they are like all other keilim and convey ritual impurity, simple leather keilim, a curtain, a sheet, or a reed mat that are not made like tents, but merely extended outward, without being on a slant or having walls, an animal or a beast that died, and impure foods or foods that were made susceptible to ritual impurity, for an impure substance does not intervene in the face of ritual impurity, and a hand mill, because it is in the category of stone keilim. All of these convey ritual impurity, but do not intervene in the face of it.
🪟 Window Thresholds
A functional window (made for use) must be at least one handbreadth by one handbreadth for impurity to pass through. A light window (made for illumination) only requires the size of a pundiyon (small coin). A window that formed naturally (water erosion, etc.) has a threshold of the full size of a fist. Intent (thought) can convert a natural opening to a functional or light window, changing its threshold accordingly.
These substances convey ritual impurity and intervene in the face of it: oversized wooden vessels, keilim made from stone, animal turds, or earth that are oversized, simple leather keilim, a curtain, a sheet, or a reed mat that are made like tents, animals or beasts, whether kosher or non-kosher, provided the head of one is placed between the legs of another and they are flush against each other, a bird that rests, one who digs out a place for a child in a grainheap to save him from the sun, and food that was not made ready to be susceptible to ritual impurity so that it would not become impure. When vegetables continue to grow in the summer and the winter, they are considered like trees and convey ritual impurity and intervene in the face of it. Among those in this category are: mint, bindweed, wild gourd, and Greek squash. Similarly, all of the following - branches of trees that hang over the earth, stones which project outward from a wall, projections, balconies, dovecotes, the clefts of stones, stones that stick out of a wall, the arches of a wall, and stony precipices - convey ritual impurity and intervene in the face of it.
The following convey ritual impurity, but do not intervene in the face of it: a human being, wooden vessels that are not oversized, because they are like all other keilim and convey ritual impurity, simple leather keilim, a curtain, a sheet, or a reed mat that are not made like tents, but merely extended outward, without being on a slant or having walls, an animal or a beast that died, and impure foods or foods that were made susceptible to ritual impurity, for an impure substance does not intervene in the face of ritual impurity, and a hand mill, because it is in the category of stone keilim. All of these convey ritual impurity, but do not intervene in the face of it.
The following articles neither convey ritual impurity, nor do they intervene in the face of it: seeds, vegetables that are still connected to the ground with the exception of the four vegetables mentioned, a mound of hail, snow, sleet, ice, or salt, one who skips from place to place, one who runs from place to place, a bird that flies freely, a garment flying in the wind, or a ship that floats on the water. All these neither convey ritual impurity, nor do they intervene in the face of it. Although they create a covering, the covering is not lasting.
🔲 Partial Closure
Closing a light window leaving a gap of two fingerbreadths height × one thumbwidth: impurity passes. Less = effectively closed. A lattice covering a large window: if any one opening is a pundiyon, impurity passes. A functional window with partial lattice: needs one handbreadth open space. A light window later covered by a building becomes a functional window (handbreadth threshold).
The following articles neither convey ritual impurity, nor do they intervene in the face of it: seeds, vegetables that are still connected to the ground with the exception of the four vegetables mentioned, a mound of hail, snow, sleet, ice, or salt, one who skips from place to place, one who runs from place to place, a bird that flies freely, a garment flying in the wind, or a ship that floats on the water. All these neither convey ritual impurity, nor do they intervene in the face of it. Although they create a covering, the covering is not lasting.
When there is a board floating in the water and there is impurity under one of its sides, the keilim under its other side are pure. The rationale is that, as we already explained, a ship that is floating does not convey impurity.
🚪 Door and Hole Rules
A hole in a door or gap between two swinging doors: size of a fist allows impurity through. A hole in a wall made to place a rod, nail, or speak through — treated as a functional window (handbreadth threshold). When a light window is roofed by a new building built outside it, its lower portion requires a handbreadth (now functional), its upper exposed portion still only needs a pundiyon.
6/7
🎓 Key Principles
Chapter 13
🪟
Window Purpose Determines Threshold Whether a window was made for functional use or for light determines the minimum size needed for impurity to pass through — one handbreadth vs. the size of a coin.
💭
Intent Functions as Action In these window laws, the owner's thought/intent (machshavah) about how to use a natural opening is treated like an actual action — it changes the applicable legal threshold.
🔲
Lattice Work: Any Qualifying Opening Transmits For a lattice over a light window, any single opening the size of a pundiyon transmits impurity — the individual holes are not combined.
📐
Roofing a Window Changes Its Category When a light window becomes enclosed within a building (covered by a roof), it transitions to a functional window requiring the stricter handbreadth-by-handbreadth threshold.