A Man Is Not a Roof

The Hook

The rule the Rambam opens with is easy to state and almost impossible to accept the first time you meet it. A covering that measures a handbreadth by a handbreadth and stands a handbreadth above the ground is an ohel, and an ohel does two opposite things at once. It carries the impurity of the dead outward to everything beneath it, and it stops that same impurity from reaching anything above it. One roof, two jobs, and they contradict each other.

Then, in the second half of the very first halacha, he takes the second job away from two classes of things. If the covering is a person, or a vessel, it still carries impurity outward and no longer blocks anything. And he presses further than you expect, because it is not only the covering itself. A plank laid across four men blocks nothing. A plank laid across four stone mortars blocks nothing, though stone can never become impure. Lay that same plank across four stones lifted out of a field, or across the backs of four animals, and everything above it is clean.

Read that slowly and you will hear what it is saying. A man may hold up a roof. He may not be one. Whatever else he can do in this world, he cannot function as insulation.

Tum'at Met 12: What the Roof Is Standing On

Chapter twelve is a chapter of measurements, and it takes them seriously in a way that reads almost comically at first. An olive sized portion of a corpse lies in a room. Needles and spits lie beside it, not touching. Cover the whole scene with something a handbreadth square held a handbreadth off the ground and the needles are impure, while whatever sits on top of that covering is clean. Reduce the covering below a handbreadth in either dimension and everything inverts. The needles beside the impurity are now clean, and whatever sits directly above becomes impure, because with less than a handbreadth of open space the Rambam treats the covering as pressed flat against the body, and untented impurity pierces upward and downward in a straight line.

If the chapter ended there it would be geometry. Instead the Rambam asks what the covering is made of and what it stands on, and the answer reorganizes everything. A person or a vessel serving as the covering, or merely as the support for the covering, conveys impurity and does not block it, and he adds the clause that decides more cases than any other line in these three chapters: this holds even where the vessels are of a kind that cannot themselves contract impurity. Four spits. Four reeds a handbreadth high. Four stone implements. All of them turn the plank above them into a conductor. Four stones, an animal, a wild beast, and the plank is a roof again.

Then comes the exception that proves he means exactly what he said. Vessels of dung, of stone, or of earth that are oversized are not counted as vessels at all. They are counted as tents, and therefore they block. The very same stone mortar, made larger, flips from one side of the ruling to the other. Nothing about the material changed. What changed is the category the thing occupies in a human household, and that is not a fact about the stone. It is a fact about what the stone is for.

The chapter walks this out through cases that reward slow reading. A board across a new oven blocks, because a new oven is not yet a vessel in this context, and the same board on an old oven leaves everything impure. And then the coffins. Most wooden coffins leave a handbreadth of space above the body, which would make the lid a genuine barrier. Some do not. The Sages therefore ruled that no coffin blocks anything, and a man who walks across one has touched a corpse.

The chapter ends in arithmetic. A round beam needs three handbreadths of circumference to have a handbreadth of width; a pillar lying in the open needs twenty four, because the square handbreadth has to survive being cut out of a curve. Then he says the thing that should be carved over the door of the study hall. All of these calculations are approximations.

Tum'at Met 13: The Covering That Will Not Last

Chapter thirteen asks a different question. Not how big, but what kind. And the first answer is startling in its generosity. An ohel counts whether it was built as a shelter or came into being on its own. A cave hollowed out by water, a burrow opened by crawling animals, a place where the earth gave way and cratered. If it covers a handbreadth, it is a tent. The law does not ask who made it or whether anybody meant it.

With one condition. It has to be sturdy. Branches hanging low, stones jutting from a wall, all of these are tents by Torah law if they could carry an ordinary ceiling and stay standing; if they would collapse, they still carry impurity by rabbinic decree but block nothing. Weakness never buys you protection. It only costs you protection.

Then the Rambam sorts the world into lists. Things that carry impurity and block it: oversized wooden vessels, oversized vessels of stone and dung and earth, curtains and sheets and reed mats when they are pitched like tents, animals lying with the head of one between the legs of the next so they are flush, a bird at rest, a man who scoops out a hollow in a grain heap to keep a child out of the sun, and four vegetables that keep growing in both seasons and are therefore reckoned as trees. Things that carry impurity and cannot block it: a human being, ordinary wooden vessels, a sheet stretched flat with no slope and no walls, an animal that has died, and a hand mill, because a hand mill is a stone vessel. Things that do neither: seeds, vegetables still rooted, a mound of hail or snow or ice or salt, a man skipping, a man running, a bird in flight, a garment blown up by the wind, a ship afloat on water.

The reason for that last list is one sentence long, and it is the heart of the chapter. Although they create a covering, the covering is not lasting. A garment in the air is a roof for as long as the gust holds. A running man is a roof for the length of his stride. The law does not deny that a covering exists. It denies that it is a covering, because a covering is not a shape, it is a commitment. And to prove it: tie the ship to something that will hold it, or weight the corner of that flying garment with a stone, and it instantly carries impurity. You did not enlarge it. You made it stay.

Tum'at Met 14: The Size of What You Meant

Having built the roof, the Rambam turns to the hole in it, and here the chapter becomes quietly astonishing. Impurity neither enters nor leaves through an opening smaller than a handbreadth square. That is the rule for a window a person cut for ordinary use. But a window cut so that light should come in has a different measure entirely, the width of a pundiyon, a small coin, and through that little disc impurity walks out of the house and lands on the man standing outside it.

Why should light be treated so much more permissively than use? Because the measure of an opening is set by what the opening is for. Function begins at a handbreadth. A window made for light is doing its work at the size of a coin, so at the size of a coin it is a window. The hole is not measured against the wall. It is measured against its purpose.

Which sets up the ruling that should stop anybody reading quickly. Suppose no human being made the opening at all. Water wore it through, animals gnawed it, the ground caved, a pane of glass broke. Then the measure jumps enormously, to the full span of a shingle, the size of an ordinary man's head, because an accident is not an aperture. Unless the owner had a thought about using it. If it crossed his mind that the gap might serve him, the measure collapses back to a handbreadth. If it crossed his mind that the gap might give him light, it collapses to a coin. And the Rambam explains himself in a clause worth the whole chapter. In these instances, thought is considered equivalent to deed.

He follows it out with the same patience. A man plastering a light window shut who is interrupted, by a shortage of cement or a neighbor calling or the Sabbath arriving, has left it open if two fingerbreadths of height and a thumb of width remain. A window open to the sky is measured at a coin, but build a house against the outside wall so that it now sits under a roof and it becomes a passage between two structures, measured at a handbreadth. Run the new roof through the middle of the old window and the lower half is measured at a handbreadth while the upper half, still open to the sun, is measured at a coin. One opening, two measures, two purposes.

The Unifying Principle

Three chapters, and they are not really about tents. Chapter twelve says that what a covering rests on determines what it can do. Chapter thirteen says a covering is only a covering if it will stay. Chapter fourteen says the size of an opening is set by what it is for, and that a thought about an opening you never made counts as having made it. Together they are a physics of influence: how what is inside a space gets out, and what it takes to be a barrier rather than a conductor.

The Alter Rebbe distinguishes between light that fills a vessel and light that encompasses it, the pnimi that enters and the makif that surrounds. A tent is the plainest makif in the Torah, which is why the sukkah is a dwelling made almost entirely of its covering. What these chapters add is that a makif is never neutral. It either passes through what it surrounds or holds it back, but it does not stand outside the transaction. There is no such thing as a roof with no opinion about what is under it.

And a man cannot be that roof. He appears in chapter thirteen in the middle list, sharing a line with wooden bowls and a dead animal and a hand mill. The Rebbe returned constantly to the idea that a Jew is placed in a situation in order to transmit something into it, that the whole purpose of being sent down into a body and a world is to conduct rather than to insulate. Here that idea appears as a legal fact with no sentiment attached to it. Stand over something and it comes through you.

The Baal Shem Tov taught that in the place where a person's thought is, there he is entirely. Chapter fourteen makes that measurable. The hole the water made in your wall is a meaningless accident until the moment you look at it and think, that could let some light in. In that instant the accident becomes a window, and the law shrinks its measure from the span of a head to the width of a coin. Nothing was cut. Something was intended, and the wall knows.

The Sfat Emet reads the temporariness of the sukkah as its whole strength, a dwelling built on trust rather than masonry. Chapter thirteen arrives from the other direction. What disqualifies the flying garment is not that it is thin. It is that it is passing.

Modern Application

Most of us believe we can be in a room without being part of what happens in it. We were present but not involved, we listened without agreeing, we were in the building but not really in the meeting. The Rambam has a ruling about this and it is not encouraging. A person conveys and does not block. Whatever was under you passed through you and reached the people on the other side, and it reached them even at the far end of the plank, nowhere near the thing itself.

The lists in chapter thirteen are worth carrying into an ordinary week. What separates the coverings that hold from the coverings that leak is almost never strength or size. It is permanence. A commitment made in a gust of feeling covers you beautifully for as long as the wind lasts, and the law does not count it as a covering at all. Tie the boat and it becomes one. Put a stone on the corner of the garment and it becomes one. The difference between a gesture and a shelter is whether you fastened it down.

And chapter fourteen is about the openings we did not make on purpose and then quietly decided to keep. Something cracks open by accident, and for a while it is only damage. Then a person notices how much light comes through it and decides not to repair it. The Rambam's phrase for that decision is that thought is considered equivalent to deed. You did not build the opening. You adopted it, and from that moment it is measured as though you had cut it yourself.

The Closing

It is the sixth of Elul, the month the Alter Rebbe described as the season when the King is out in the field, which is to say the season when the ordinary coverings are down. These chapters spend all their patience on exactly that question. What comes through, what holds it back, and whether the covering you are relying on is fastened to anything.

You cannot be a wall for the people standing behind you. That was never on offer. What you can do is decide what you are standing over, and how long you intend to stay there, and whether the opening you have been meaning to close is one you have quietly started calling a window.