Rambam - 3 Chapters a Day

A covering that is a square, a handbreadth by a handbreadth and a handbreadth high brings ritual impurity and intervenes between ritual impurity according to Scriptural Law. For an ohel is given that distinction only when it is a handbreadth by a handbreadth and a handbreadth high or more.

What is implied? There was an olive-sized portion of a corpse lying with open space above it and implements (keilim), e.g., needles and spits, were at its side, without touching it. If one covered the portion of the corpse and the implements with an ohel that was a handbreadth by a handbreadth and was more than a handbreadth above the ground, the covering conveys impurity to the implements and renders them impure.

If there were other implements on top of this ohel that was a handbreadth by a handbreadth, they are pure, because the ohel intervenes between them and the impurity. Thus we have learnt that just as an ohel imparts impurity to everything that is under it, it preserves the purity of anything outside it, and intervenes between the impurity and the implements that are on top of it. Similarly, if the impurity was above the ohel and the implements were below it, the implements are pure, because the ohel intervenes in the face of impurity.

If the ohel was less than a handbreadth high or less than a handbreadth by a handbreadth, even if it was several handbreadths high, the implements that are next to the impurity are pure. Any of the implements that are above this ohel and are directly above the impurity are impure. The rationale is that they were positioned over the impurity and there was no ohel intervening in the face of the impurity. Similarly, if there was impurity above this ohel and implements beneath it, any implements that are directly beneath the impurity are impure, for the impurity was hanging over them and there is no ohel intervening in the face of the impurity. The rationale is that whenever there is less than a handbreadth of open space, it is considered as touching and the impurity under it is considered as "flush," as we explained.

When does the above apply? When the ohel was not a person or an implement. If, however, a person or an implement serves as an ohel over the impurity, whether they were the covering itself or the support for the covering, even if the implements were such that themselves do not contract impurity, they convey impurity and do not intervene in the face of impurity.

What is implied? If there was a board placed upon four men or on four implements, even stone implements or the like that do not contract impurity or, needless to say, if they were placed on four spits or four reeds that were a handbreadth high, and there was impurity and other implements beneath it, those implements are impure. If the implements were on top of the board, even if they were not directly above the impurity, they are impure. If there was impurity above the board and implements below it, all of the implements below the board are impure. If, however, the board was placed on four stones or on an animal or a beast and there was impurity under it, the implements on top of it are pure.

If there was impurity on top of a board, all of the implements under it are pure, because the ohel intervenes in the face of the impurity. Implements made from animal turds, stone implements, or implements made from earth that are oversized are considered as ohalim and not as implements. Therefore, they intervene in the face of impurity.

The following laws apply when a board was placed on top of a new oven and it protrudes beyond the oven on either side for more than a handbreadth. If there was impurity below the board, implements that are on top of it are pure. If there was impurity on top of it, the implements below it are pure. The rationale is that a new oven is not considered as a k'li in this context. If the oven was old, everything is impure.

When a board was placed over two ovens, even if they are old, and it protrudes beyond each oven and there is impurity below it, between the two ovens, only the space between them is impure. Keilim that are beneath the two ends that are beyond the ovens are pure, for the area beneath the ends and that beneath the ovens are considered as two tents, one next to the other.

Similarly, if a board was placed over an oven, even an old one, and it protruded a handbreadth at both ends, but not from the sides, should there be impurity under one end, keilim under the other end are not considered as impure.

The following laws apply when a person carries a k'li, e.g., a plow or the like, and one side of the k'li hung over impurity. If the circumference of the k'li was a handbreadth, even though its width was only a finger breadth and a third, it imparts impurity to the person carrying it. Impurity is conveyed to him according to Rabbinic Law, for our Sages decreed impurity for a k'li whose circumference is a handbreadth as a safeguard lest one be lenient when there is one whose width is a handbreadth. It does not, however, convey impurity to keilim that are below it or other people over which it hangs unless its width is a handbreadth.

Wooden coffins in which a corpse is placed are not considered as graves. Instead, if there is a handbreadth of empty space between the covering of the coffin and corpse, the cover is considered as an intervening substance and one who stands on the cover is considered as pure according to Scriptural Law. Nevertheless, although most coffins have an empty space of a handbreadth, since there are some which do not have such space, our Sages decreed that no coffin would be considered as an intervening substance. Thus one who walks on a coffin is considered as if he touched a corpse or a grave.

The following laws apply when a beam extended from one wall to another wall and there was impurity under it. If it was a handbreadth wide, it conveys impurity to everything under its entire span. Any keilim or persons under it are impure. This applies even if its width is not the same along the entire span and some portions are less than a handbreadth wide. The rationale is that these portions are considered as part of an ohel. If it is not a handbreadth wide, the impurity pierces through and ascends and pierces through and descends, as we explained.

How much must the circumference be for the board to have a width of a handbreadth? If it is round, three handbreadths. If it is square, four handbreadths.

When a barrel a se'ah in size was on its side in an open area, it does not convey impurity to everything under its entire expanse unless it is approximately four and half handbreadths in circumference. In this way, its upper portion will be a handbreadth and a half above the ground and there will be a portion of it, a handbreadth by a handbreadth a handbreadth above the ground. Accordingly, if it was suspended half a handbreadth above the ground and its circumference was three handbreadths, it conveys impurity.

Similarly, if there is a round pillar lying in an open space and resting on the earth, it does not convey impurity under its side unless it is 24 handbreadths in circumference. If it is not 24 handbreadths in circumference, the impurity pierces through and ascends and pierces through and descends. The reason that 24 handbreadths are required is that whenever there is a circumference of three, there is a width of one. Whenever there is a square, a handbreadth by a handbreadth, its diagonal will be a handbreadth and two fifths. Therefore if the pillar's circumference was 24 handbreadths, there is a little bit more than a handbreadth by a handbreadth that is a handbreadth high under its entire side. All of these calculations are approximations. This is its form.

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. An 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.

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.

If one tied a ship to something that could anchor it or covered the corner of a garment with a stone, it conveys ritual impurity.

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.

The following entities intervene in the face of ritual impurity, but do not convey impurity]: the threads of the woof on a weaver's loom, the cords of a bed, a net on which fertilizer is held, and lattice shades for windows.

How do they intervene in the face of impurity? If there was a window between two houses, impurity was found in one house, and one of these entities is extended over this window and covers it, it serves as an intervening substance and prevents impurity from entering the second house. This applies even if there is open space within the intervening article, provided there is not a square handbreadth of empty space in this lattice work, net, or cords. If there is a square handbreadth of empty space, impurity will enter as will be explained.

Impurity does not enter a shelter, nor does it depart from it if there is an opening less than a handbreadth by a handbreadth.

What is implied? When there is a window between one house and another or between a house and a loft, if it is a square handbreadth by a handbreadth and there was impurity in one of the structures, the other structure is also impure. If the window does not comprise a handbreadth by a handbreadth, impurity does not depart from it, nor does it enter the second structure.

When does the above apply? With regard to a window made by a person for functional purposes. When, by contrast, a window was made by man for illumination, that light should enter, its measure is the size of pundiyon. Then ritual impurity departs through it.

What is implied? There was impurity in a house. A person came and stood on the outside, near this window for light or placed a k'li there, or there was a covering on the other side of the wall, the person, the k'li, and everything under the covering to which the impurity passes through becomes impure. A window made for light is one that is not covered by a roof, but instead, is open to the sun.

When an aperture was not made through intentional human activity, e.g., it was hollowed out by water or crawling animals, the earth itself cratered, a window had been shuttered close and the shutter was removed, or it had been covered by glass and the glass broke, the minimum measure is the full span of a shingle which is the size of the head of an ordinary man.

The above applies provided that the owner did not think of using that aperture for functional purposes. If, however, he thought of using it, the minimum measure is an opening of a handbreadth by a handbreadth. If he thought to use it for light, its measure is the size of a pundiyon. The rationale is that, in these instances, thought is considered equivalent to deed.

The following rules apply when a person began closing a window opened for light and did not complete the task because he did not have sufficient cement or a colleague called him, night fell initiating the Sabbath, and there remained a small amount open. If a portion the height of two fingerbreadths and the width of a thumbbreadth remain, it conveys ritual impurity. If it is less than that, it is as if it was closed.

The following rules apply when there was a large window made for light covered by a lattice or the like. If there was one place where there is a hole as large as a pundiyon, it conveys ritual impurity and allows ritual impurity to depart. If the holes of the lattice are small and not one of them is the size of a pundiyon, it is considered as closed. Similarly, when there was a large window made for functional purposes and it was covered by thatchwork coverings or shades, if there was empty space a handbreadth by a handbreadth square, it conveys ritual impurity and allows ritual impurity to depart. Otherwise, it is considered as closed.

When a window is exposed to the open air, its minimum measure is the size of a pundiyon, because it is made solely for the purpose of light, as we explained. If one builds a house outside this window and thus the window is now under a roof, it is considered as if it is between two structures and its measure is a handbreadth by a handbreadth of empty space. If the roof was built in the middle of the window, the measure for the lower portion that is below the roof is a handbreadth by a handbreadth of empty space. The measure of the upper portion that is above the roof is the size of a pundiyon, because it is exposed to the open air.

The following rules apply in the situations to be described: There is a hole in a door, a carpenter left an empty place above or below or hung two swinging doors and did not complete adjusting them and thus there was empty space between the two doors, or he closed the door and it was blown open by the wind. In all these situations, if the opening was the size of a shingle, the impurity leaves through this opening and enters through it. If the opening is less than the size of a shingle, it is considered as closed.

When a person makes a hole in a wall in order to place a rod or a large nail there, to see those who pass by, or to speak to his colleague, it is considered as a window made for functional purposes and its minimum measure is a space a handbreadth by a handbreadth.