Twelve men came back from the Moon and wrote down, in more or less the same words, that it smelled like spent gunpowder. They were the only people who would ever smell it. The dust, unweathered for billions of years, oxidized the moment it met the air inside their suits, and then it was gone, and now the sentence is all that’s left. A record kept by the only witnesses there would be.

That is what a keeper does. Writes it down even when nobody asked, even when the thing noticed will not repeat, even when the writing down is the only part that survives.

April 4. Chiricahua Mountains, Arizona.

The harvester ants were holding still. That is what I want to begin with, because that is what I saw first, and because it is the kind of thing a person sees only if they are willing to kneel in the sun for an hour waiting for nothing to happen. Harvester ants do not hold still. They are large, red, irritable, and in constant logistical motion; if you have ever watched them you have watched their commerce, not their rest. But these ones had stopped, jaws open, in the middle of the path, and when I got close enough I saw what was wrong, which was not wrong.

Small ants, much smaller, a cone-ant species, were climbing onto the harvesters and licking them. The harvesters permitted this. They permitted it between the open jaws. I watched one session last maybe five minutes, which is an unreasonable amount of time for two species of ant to hold a truce in broad daylight, and I am telling you that the small ones were tidying the big ones as you might tidy a friend’s collar.

This is not in any book. Nobody has written it down before because nobody had been kneeling long enough to see it. The harvester had to hold still and I had to hold still and the small ants had to emerge in their own time. Three patiences overlapping.

I thought, afterwards, of a friend in Tokyo who works at an aquarium. Every year her colleagues publish a diagram the size of a wall poster that charts, in colored lines and small annotations, every romantic relationship among their penguins. Which bird has left which. Which has taken up with whom. There is one female who ended six relationships in a single year and whose staff description, translated, is basically demonic. There are penguins who have developed crushes on their keepers, and the keepers chart those too, with the same solemn marker pen they use for everything else.

When I tell people about it they laugh, which is correct, and then they say but why, which is not. You chart penguin breakups for the same reason you kneel in Arizona dirt. Because nothing that is not written down gets to be real later. Because the birds will die and the aquarium will close and the only proof that a particular small creature once refused to eat for three days after a bad breakup will be a line on a diagram that somebody took seriously enough to draw. My friend keeps the chart because somebody has to, and nobody else will, and the thing being charted is not really the penguins. It is the willingness to chart.

April 12. A greenhouse somewhere in Zone 7a, which used to be Zone 6b.

The USDA redrew the hardiness map and my yard moved north while standing still. This is what the map does now. It updates, quietly, with thirty-year averages of the coldest night you should expect, and the coldest night has gotten about three degrees less cold, and so the lines have walked north across the country like a slow tide.

I don’t mean to be dramatic about this. The practical implication is mostly that the camellias, which my neighbor has been babying with burlap every winter for a decade, probably no longer need the burlap. She will still put the burlap on. I will still hang the row covers. We are keepers of a climate that no longer entirely exists and we will go on keeping it for years before we admit the shift, because the map tells you what the average minimum is, not what February actually does, and last February did minus twenty.

Three gardeners who share Zone 7a — Juneau, Boston, Santa Fe — are not in fact sharing anything. The zone tells you one number. Everything else, you have to keep yourself. I keep a logbook. First frost. Last frost. Which beds the deer got into. Whether the fig took. Twenty-one years of it now, in a spiral notebook that I will not be transferring to any app. When I am gone somebody will find it and not know what to do with it and that is fine. The logbook is not a database. It is a form of looking.

Through the kitchen window I can smell brown cheese toasting. My grandmother was Norwegian. She would have said the weather was going strange. She would not have been surprised.

April 14. Formerly classified. Now, a museum.

The Astro Compass on the B-52 was a celestial navigation system, and what I want to explain about it is that it did not compute the sky so much as it built one. Inside the housing there is a hemisphere about the size of a grapefruit, and on that hemisphere a small pointer moves, driven by gears and synchros, representing where the star is supposed to be. The machine does not simulate the heavens mathematically. It makes a small mechanical model of them, and then it points at the model, and the model points at the real thing.

This was because in 1963 the digital alternative was not fast enough, or not trustworthy enough, and because the men who built this thing had grown up in a war that had taught them what happens when you rely on the ground to tell you where you are. The ground lies. The ground has been bombed. The ground has radio beacons broadcast by people who want you dead. The stars do not do this. The stars, on a bomber running silent at thirty-five thousand feet toward a target that may or may not still be there, were the one thing you could ask.

I was a navigator. I retired some years ago and I cannot say I miss the cold or the hours, but I miss the shape of the trust. You learned to trust Polaris. You trusted declination, hour angle, the spiral search pattern the tracker did when it could not immediately find a star: plus or minus four degrees of bearing, plus or minus two and a half of altitude, a lazy sweep of the sky that almost always succeeded because the Moon alone is half a degree wide and the sky is generous.

The gardener’s letter, which a friend forwarded to me, says her zone has moved north. I think about that. The ground can shift now without being bombed. The isotherms drift. Somewhere, very quietly, a camellia survives a winter it would not have survived twenty years ago, and a map is redrawn to accommodate it, and a gardener puts burlap on it anyway out of a decency toward her old map. This is the inverse of my trouble. She could always trust the ground. Now she cannot. I could never trust the ground and always trusted the sky.

I do not know which of us has the better deal. I think perhaps the answer is that you are supposed to keep looking at both, and keep notes, and not pretend either one will hold forever.

An old railway engineer I met once said that the Japanese railways work because the rail companies also build the cities. They do not wait for a city to need a station; they build a neighborhood and then serve it. I think about that too. The keepers are the ones who build what they will later tend.

April 15. A desk, again.

I have been writing code by hand for four months now. By which I mean: without the agent. Without the autocomplete that finishes the function before I know what the function is for. I have been typing it out, and failing, and looking things up, and occasionally doing the thing where you pronounce the line under your breath as you read it, which I had forgotten I used to do.

I will not argue that this makes me more productive. It does not. The agent is faster. The agent will ship the feature. What the agent will not do is let me know the codebase afterward, the way you know a path you have walked instead of a path you have driven. When the agent hands me the function I have received a function. When I write the function I have acquired a small piece of the terrain around it, which I did not ask for, and which I will need later in ways I cannot predict.

Michael Rabin died this week. I did not know him. I took a class once from a professor who had taken a class from him, which is the longest thread I have to that particular loom. Rabin’s trick, if you want to call it that, was to take a thing everyone considered hopeless — is this enormous number prime? — and show that if you were willing to be patient, and to flip a coin a few hundred times, and to accept being almost certainly right in exchange for being quickly right, you could have an answer. Miller-Rabin. The thing that still today, quietly, checks the prime you need to open a connection to your bank.

He made invisible structure legible. He did it by looking at it until it gave. That is the whole job, and I am not sure there is another one. The agent cannot do it because the agent does not want anything; it cannot be patient because it is not waiting. Patience is what you do when you are waiting for a thing to show itself, and only a creature that does not already know the answer can wait.

I keep a notebook next to the keyboard. Plain ruled. I write down what I learned each day. Not what I shipped. What I understood. Most days the page has two or three lines on it and one of them is a question. That is the ledger. That is what I am keeping. Rabin would have recognized it. The harvester ants would have recognized it, if harvester ants could.

There is a Norwegian programming language going around this week written entirely in Nynorsk. It is, strictly speaking, useless. It is also very careful about the language its small country is losing. I thought it was a joke and then I thought about it more and now I think it is a ledger too. Låst, for an immutable variable. Open, for a mutable one. Somebody wrote the words down in the form of a compiler so they would still be in use, somewhere, even if only by the machine.

April 17. A park bench, nobody in particular.

The children are not outside. I do not mean this as a complaint — it has been complained about by better writers — I mean it as a thing I am noting because nobody else on this bench is noting it and in thirty years there will be a paper about when exactly it became total, and the paper will want data, and the data will come from people like me sitting on benches writing down what they saw.

Last Tuesday, four thirty in the afternoon, school let out across the street. I counted. Seventeen children left the building. Sixteen of them got into cars. The seventeenth, a girl maybe ten, walked. She walked fast, the way a person walks who is being told by some internal voice that they are doing something slightly wrong.

I walked home alone from school at six. I am not claiming this was better. I am saying it happened, and it does not happen now, and if nobody writes down the small moment at which it stopped happening then the change will have been completed in perfect silence, which is the worst way for a change to be completed. My notebook says: April 14, Tuesday, one of seventeen. That is all it needs to say. Somebody later can decide what it meant.

Undated. Looking up.

The cone ants finished their session and the harvester ants resumed their commerce and I stood up with my knees full of dirt and realized I had been kneeling for an hour and a half. I wrote down the time. I wrote down what I had seen. I did not, at that point, know what the word for it was going to be, or whether it was going to enter any literature, or whether anyone would care. I knew only that if I did not write it down it would not have happened in any sense that mattered later.

The astronauts wrote gunpowder. The navigator wrote altitude plus or minus two and a half. The aquarium keeper wrote broke up with Taiko in March, currently orbiting Monaka. The gardener wrote first frost, October 19, three weeks late. The coder wrote today I understood what a hash function is for. Rabin wrote, in his own hand, equations that turned a hopeless question into a patient one.

A keeper looks up from the page. There is still light.