The first work on the dam began a week before Sandy arrived, when building materials were taken to the site. As weather forecasters were hemming and hawing about European versus American climate models and Mayor Bloomberg was debating whether to evacuate flood areas, New York City Transit was working on its own hurricane plans. “You scramble your jets right away — you can’t wait,” says Thomas F. Prendergast, president of New York City Transit at the time and now the authority’s chairman and chief executive. The reports on the dam that he was getting at the Rail Control Center in Midtown showed the level getting higher and higher. “The water was lapping at the top,” he says.

Not long after Sandy was categorized a tropical depression off the coast of Venezuela on Friday, Oct. 19, the M.T.A. had begun gathering cots and bedding, food and water, for track workers and hydraulics teams and even the train crews that would shut the system down and start it back up. Carpenters and bus drivers alike would be staying at depots and temporary shelters, because there would be no way for them to go home and then return to work while the subways and regional trains like Metro-North Railroad and New Jersey Transit were out. By Wednesday, when Sandy crossed the island of Jamaica as a Category 1 hurricane, carpenters were covering sidewalk subway grates with plastic sheeting and plywood and building barriers at the entrances of low-lying subway stations, mostly in Lower Manhattan.

On Sunday, as Sandy moved up the East Coast, Governor Cuomo announced the closing of the subway system. “Now it is time to take action,” he said. Transit put its trains on tracks between stations north of 59th Street, where many tunnels are at a flood-safe elevations. Engineers and conductors walked back along the tracks to be picked up by the dwindling number of trains still running.

At the 148th Street Station, in Central Harlem — the northern terminus of the Seventh Avenue line, a.k.a. the No. 3 line, and the point where the tracks go underground beneath Lenox Avenue — Frank Jezycki was watching carpenters build the dam. Jezycki is in charge of all subway maintenance, which includes tunnels, elevated structures, fans and pumps. Pumps are always going; on a dry day, the system takes in 13 million gallons of water that pour into it from underground streams and other sources. “My area is responsible to, first, try to mitigate the water coming in,” Jezycki says, “and, second, to get rid of the water once it comes in.”

Jezycki had recently been going all around the subway system — “That guy Frank,” a hydraulics worker said, “he’s a machine!” — but now he was focusing on the dam-building as the timbers, plywood and sandbags were moved, fire-brigade style, from the M.T.A. yard at Lenox Avenue down to the tunnel’s opening. There were already two vertical steel supports on each side, installed before a Nor’easter in 1992 to hold a three-foot-tall dam, like the one that kept out the water from Hurricane Irene in 2011. It took about five hours of construction to put up the three-foot dam across the tunnel’s mouth.

But Jezycki and the carpenters were worried. Sandy was expected to be bigger than Irene: the storm was due to arrive at the same time as the high tide, which was going to be higher than normal because of a full moon. What’s more, the Harlem River was not the only threat at 148th Street; water sometimes runs off the Harlem River Drive, and out of the sewers. “We’ve had occasion where the sewer becomes surcharged and overflows through the manholes into the yard,” Jezycki says, “and flows down the track to the portal.”

Around 4 that afternoon, Jezycki called the head of track engineering, Antonio Cabrera, back at the command center. “Hey Tony,” Jezycki said, “we’re at the 148th Street portal. It doesn’t seem right. We don’t think we have enough height here.”

Cabrera consulted the National Weather Service’s Slosh maps, which provide the estimated levels of Sea, Lake and Overland Surges from Hurricanes. Cabrera came back with a new number, which Jezycki relayed to the carpenters.

“This is what we need to do, fellas,” he said. “We need to get this wall to eight and a half feet high, and it’s going to need to hold back the Harlem River. You need to build it at such a strength that is going to endure.”

Joe Valentino, a carpenter who for decades has made concrete forms, walls, all kinds of temporary structures for the subway system, recalls the 148th Street dam as imperfectly done — it was made in two phases when he would have preferred one — but good enough: “Is there something we could have done that would have worked 10 times better? I would say yes. Under the circumstances, it obviously worked pretty damn good.”

It endured, with about three inches to spare. The triumph might seem like a small one in the face of Sandy’s destruction, but it wasn’t. Here’s what it prevented from happening: After flooding the No. 3 line tracks to the south, and destroying millions of dollars worth of equipment, the Harlem River would have continued south, following Lenox Avenue to about 142nd Street, a junction where the 3 line joins the 2 line, which runs to and from the Bronx. By consulting both the Slosh maps and its own topographical maps, the transit authority determined the water would have flowed toward the Bronx, via what’s called the Harlem River-Lenox tunnel, and then east to 149th Street on the Grand Concourse. Then, in the worst case, the water would have moved through a connecting track, and like liquid moving through a Krazy Straw, the Harlem River would have flowed south through another under-river crossing, the Harlem River-Jerome tunnel, to 125th Street in Manhattan. From there, it would have flooded the downhill Lexington Avenue line — which happens to be the busiest one in the city, carrying more people every day, 1.8 million of them, than any other American subway system — to about 103rd Street, where the tracks rise, up toward Carnegie Hill.

“It’s all downhill — the Harlem River never breaks a sweat,” Jezycki says. “That’s all based on the elevations.”

‘TO UNDERSTAND WHAT THEY WENT THROUGH . . . ’

The subway is the Mississippi River of personal commerce in New York, for people who work in Midtown, Dumbo, Wall Street. For three days after Sandy hit, it was stopped dead, and for another two days after that, only part of it was running. The closure proved once again that New York does not function without its subway. It doesn’t get to work, and when that happens, it doesn’t make money: hundreds of millions of dollars worth of economic activity didn’t take place every day that MetroCards were not being used.

But the patchwork system, a hundred years old in some places and brand new in others, works. It gets people around. Engineers and track workers, everyone from station attendants to carpenters — somehow keep it going with fixes and advance preparations. It can’t be wholly turned off for systemwide upgrading — the region’s economy is too dependent on its running every day.

Despite all the millions that have already been spent on upgrades — in 2007, $157 million was allocated to flood prevention, including the M.T.A.’s Operation Submarine, which provided barriers for subway entrances, raised ventilation grates and established disaster procedures — Sandy made M.T.A. workers look like a bunch of children racing around the beach as a wave came in toward their sand castle. Sometimes it felt that way to them too. The Federal Transit Administration describes Sandy as the nation’s worst transit disaster. But the M.T.A. weathered the blows, fashioning a makeshift subway on the fly. Days afterward, Gene Russianoff, of the Straphangers Campaign, a subway riders’ advocacy group, used the word “magic” to describe all that went into getting a Sandy-hobbled system up and running again.

“The system was put back together with temporary repair,” says John O’Grady, an M.T.A. engineer who is in charge of both ongoing recovery from Sandy and preparing the system for a wetter, bleaker future. (A study in the journal Nature Climate Change concluded that New York’s annual flood damages will rise to $2 billion by 2050.) “To understand what they went through to put it back together — it’s a phenomenal process.”

When you look closely at it now, a year later, in the midst of another Atlantic hurricane season, you see all the ways in which the Metropolitan Transportation Authority and New York City Transit failed and triumphed. And you see what it will take to keep the system going: technological improvements, yes, but also the oldest technology of all — the knowledge of the people who run the subway, many of whom have been there for their entire working lives.

This year, should a Sandy-like storm show up, it won’t encounter a transportation system that has changed conspicuously. But the thinking of the people running it has. As one senior official puts it, “We definitely had tremendous lessons learned.”

‘COMPLETE SILENCE’

After the trains were stowed by Monday, and all the train signals that could be taken out of the tunnels were removed by signal workers — the transit employees who wire and rewire the lights and relays that make it possible to run more than one train on a set of tracks at a time — something happened at the Rail Control Center that has happened only a few times before. The R.C.C. is the computer-crowded nerve center of popular imagination. There is a desk in charge of stations (468 of them) monitoring turnstiles, staircases and MetroCard machines. There are desks for communications, car equipment and customer calls, and one for signals, tracks and infrastructure. A cop sits at one desk. The trains are on the boards, the term for the illuminated schematics that cover the long walls. The boards are always lighted, detailing power supplies and the status of everything from pumping stations to communications equipment, until they all eventually — on the day Sandy arrived — began to dim.

The system was being powered down. The tide was close to waxing, and only a few people were underground, so nothing at all was moving on the R.C.C.’s boards.

“And then,” says Joseph P. Leader, a vice president and chief maintenance officer, “the most amazing thing happened that you don’t see too often in the R.C.C. — complete silence.” The boards seemed broken. “You didn’t see a train on the board move. Once in a while you would pick up a phone and say, ‘Does it work?’ ”

Since Hurricane Irene, the M.T.A. has had an employee act as a “scribe” — officially, the Information Liaison Officer — for the duration of extreme events, like hurricanes and snowstorms. The scribe keeps what’s called an “incident chronology,” a disaster-response timeline, for the sake of institutional memory and in case there are lawsuits or the City Council complains and the authority needs to justify its actions.

The scribe sits in the situation room, overlooking the R.C.C. For both Irene and Sandy, Dan Mazzella, a native New Yorker who normally works in train scheduling, filled the role of scribe. In the hour or two before Sandy hit, Mazzella was not busy. He likens that period to a break in a symphony’s performance. “The conductor’s up like this,” he says, raising a hand, “and you have absolutely no control over when the baton drops, but you know that like a bat out of hell it’s going to happen.”

Then, inside the control center, the TV told them the surge had arrived. “All of a sudden the phones start lighting up, and you don’t have enough hands, you don’t have enough ears,” Mazzella says. “It’s nuts, the 6-Wire” — the internal communications line, which connects to the Police and Fire Departments — “starts going off, and you’re hearing that there are explosions down at the Con Ed plant, that there’s water cascading into the system here. . . .” The boards began to come back to life, the sensors in the tunnels registering the water as moving trains. New York City Transit had estimated that flooding would close a few of the 14 tunnels that go under the city’s waterways (called “tubes”), but at this time it looked as if nine of them would be lost.

‘REALITY SET IN THAT THIS IS BAD’

Among the many places where the Hudson and the East and even the Harlem Rivers breached the New York City subway system when Sandy finally hit, the recently completed South Ferry station was high on the list of the most overwhelmed. At around 10 o’clock that Monday night, just after the first of Sandy’s two major surges — one came from the south, from New York Harbor; the second came from the north a few hours later, from Long Island Sound — a National Guard truck dropped off Joseph Leader at the bottom of Broadway, so he could wade past Battery Park to check out the South Ferry station.

He already knew things were worse than anyone expected. During Hurricane Irene, in August 2011, flooding at Battery Park was bad — but not three-feet-of-water-over-Lower Manhattan bad. The area was a lake, the subway stairs at the South Ferry entrance a small cascade. As Leader was imagining all-new worst cases in his head, another engineer shouted at him. “He said to me, ‘I just got a call from Con Ed, and there’s like a 26-foot surge or wave that’s coming into the bay that they got alerted of, and they are shutting down the 14th Street plant.’ And before we could absorb that, we could see power shutting down in the city. So that was a moment when you started to say, ‘Oh [expletive].’ ”

Leader went south, toward the Staten Island Ferry landing, where he saw the first unexpected worst-case scenario: the plywood-and-plastic-sheeting barricade at the mouth of the South Ferry entrance had been trashed by timber washed in from the harbor. Then he waded back north, to the station’s other entrance, to look in on a spot where there wasn’t supposed to be flooding, even in hurricanes. But as soon as he started down the stairs at this entrance, the beam from his flashlight hit water. “Where is the water going?” he wondered. Even someone who had worked for the system since 1986, who can rattle off the names of pump stations with ease — the Mud River pump room at 60th Street, for example — was confused by what he saw.

Slowly, Leader came to understand that the water was not just coming into the station from the harbor — it was also leaving the station, heading north on the tracks, as if taking the No. 1 line uptown. Worse, it was about to enter into the Lexington Avenue subway line’s tunnel through an underground track connection invisible to riders. The M.T.A. was facing an underground assault after having mostly built its fortifications aboveground, at station entrances and vents. The other thing Leader realized as he watched the water climb the stairs in front of him was that he had to get out of there, fast.

He rode the National Guard truck back uptown, through a now-dark city, and 20 minutes later, in the Rail Control Center, where many engineers would live for the next week, he began to receive reports of explosions in the subway. This was before the second surge. “Reality set in that this is bad,” he says. “But at this time we still didn’t know the extent of everything.”

A couple of days later, what would have been worst-case scenarios had become almost expected, and Leader was changed by the experience. So was the M.T.A., which would now have to make flood prevention at the South Ferry station a major priority. After subway service was cobbled back together, after Leader got to spend a few nights at home, he returned to the bottom of the South Ferry stairs and walked through the lately flooded station that was finished being built in 2009 for $527 million — its wires now corroded after their exposure to salt water, muck on the white-tiled walls, the whole place an ancient-seeming ruin — and thought about how the harbor chased him up to the street. “There are just some times when you realize that Mother Nature is bigger than anything you can do,” he says.

‘VINTAGE EQUIPMENT DID A BETTER JOB’

Immediately after the first surge hit, Frank Jezycki, the chief infrastructure officer, had teams out inspecting the damage. Some inspectors were aboveground — they would see that the A line across Jamaica Bay was completely destroyed, for example. Others were underground, after opening manholes and hatches in sidewalks and walls or getting into the system through emergency exits, and then walking the powerless tunnels in the dark. It was mostly bad news.

Clarence Facey was one inspector among the 20 teams out in the under-river tubes; a few hours later, he was one of the hundreds of workers pumping them out, nonstop, for days. “It was like working on a ship — rest four hours, and then you’re back out there,” he says. “The first four days it was 24-7.” To inspect the F-train tunnel, he entered at the East Broadway station. It was dead quiet at first, but as he moved farther in, he heard a strange sound. The tunnel was flooded almost to the ceiling, but a draft moving through a narrow, mile-long airway was producing an eerie, constant whistle. “A strange sound, I’ll say,” Facey recalls.

The other sound he heard was at the Manhattan end of the Lexington Avenue line’s under-river tube — the Joralemon Street tunnel — which he entered via an emergency exit at South Ferry. What he heard there was as familiar to a tunnel inspector as a robin’s call is to a bird-watcher — a hard, rhythmic chug: chhhh . . . chhhh . . . chhhh. . . .

It was the sound of old-school subway technology, a pneumatic pump powered by pressurized air from pipes that run all the way back up to 149th Street, where a compressed-air station was unaffected by Con Edison’s power outage downtown. There are dozens of air-compressor pumps all along the Lexington Avenue line; each one of them removes about 200 gallons of water per minute and is about 60 years old, having replaced early-20th-century models. Jezycki refers to these pumps as his Studebakers. They were struggling, but succeeding enough to keep the tunnel clear, draining the water that chased out Joe Leader before flowing downhill toward the East River tube. Aboveground, the plywood had kept the water out of the air vents.

“I would say I was pretty surprised there was no water in the Joralemon tunnel,” Jezycki says.

Facey says, “In this case vintage equipment did a better job.” He remembers entering the tunnel, turning to the other inspector and shouting: “You hear that? You hear that?”

‘I DIDN’T KNOW WE COULD TURN THERE!’

By 8 a.m. Tuesday, Sandy was gone, and pump trains were in the tunnels. The first of the six cars that make up a pump train is equipped with four pumps, powered by a diesel generator, that push 4,500 gallons of water a minute through a hose back up into the harbor. The hope was to get two or three tubes pumped dry by Wednesday. And the signal department was preparing to put back the signals that were taken out, though in the Montague Street tube — the oldest line, where the signals were too complicated to remove temporarily — that process would ultimately take more than a year and force the rerouting of 65,000 commuters daily. This is in contrast the L line, and its Communication Based Train Control, which enables trains to communicate with one another and with the command center, skipping old-fashioned signals and operating without an onboard engineer. (C.B.T.C. will next be put on the 7 train.)

“The wild card thrown at you was the Con Edison blackout,” says Peter G. Cafiero, chief operations planning officer, in charge of subways, buses and the Staten Island Railway. After the surges passed, many of the subway lines were crippled more by power loss than by flooding. When the assessments were in, Cafiero faced a puzzle that would cost the city’s economy tens of millions of dollars a day as long as it went unsolved. “We couldn’t run a full service from the Bronx and Queens and Upper Manhattan into 34th Street and turn them back,” he said. “It wouldn’t work, and we had the additional problem that for all of Brooklyn there was really no way to get to Manhattan by rail.” They had created emergency plans for blackouts. “But if there is a blackout, you are usually looking at the whole city out, and you are just trying to bring people home ’cause they are not going to come back to work if there’s no power,” Cafiero says. “Here we had half the city blacked out and half the city not. People wanted to get to work, and they couldn’t.”

The heads of different M.T.A. and transit sections — Leader and Jezycki, along with Ken Mooney, the head of engineering, and Wynton Habersham, transit’s chief electrical officer — met every hour, along with Prendergast and Joe Lhota, who was the head of the M.T.A. at the time. The big problem: The power failure had cut out the middles of five of the lines that run through Manhattan. A railroad needs a terminal, where a train can turn around — that is, be threaded off its downtown tracks and onto an uptown line. Grand Central Terminal, on the Lexington Avenue line, is grand and central but a terminal only for commuter trains. The subway station at Grand Central consists of narrowly spaced tracks, with limited switching capacity.

The solution was to create makeshift terminals in Midtown, to turn trains quickly on tracks that were not designed to reroute trains. At some point, they realized that what they were trying to do was a version of their newest overnight repair operation, called Fastrack, which completely suspends work on one part of a line — a segment in Brooklyn, say, over the weekend, or during the night for several weeks — while passengers are shuttled around it on other lines. They would try applying Fastrack on every line at the same time.

Temporary terminals were created at 34th Street and Herald Square and near Grand Central. If Act I after Sandy hit was about the surprising extent of the devastation it wrought, Act II was about the resilience of the system’s human capital, people who had spent their lives in it. Longtime engineers were taking advantage of historic aspects of the system’s workings that the newer engineers didn’t necessarily know about.

“Our maintenance people are kind of amazing for what they can pull out of their hats,” Cafiero says. “And one of the key things that I felt in the control center is that we had myself, train operations and people who knew the electrical power systems” — including how voltage could be supplied to stations in makeshift ways. Examples of the kind of questions coming from Cafiero: Do I have power for switching a train to run north of 42nd Street? Can we get a generator in there for station lighting? “Some of this is about having the knowledge in your head about what you can do at any given point in the system,” he says. He recalls saying more than once, “I didn’t know we could turn there!”

THE BUS BRIDGE: ‘OUR FINEST HOUR’

The end was in sight on Thursday, 51 hours after the first surge. Test trains were running; service was coming back from the Bronx and Upper Manhattan into Midtown. But there was one hurdle: Con Ed had not yet restored power to Downtown. The M.T.A. needed time, as well as a way to get customers from Brooklyn and Queens, across the East River and into Midtown. The M.T.A. needed a bridge, so it created one and named it the Bus Bridge. Transit planners around the world will be discussing the feat for years, even though New Yorkers will not. The bus bridge was a band-aid for the disabled subway system, formulated on Wednesday evening and executed at dawn on Thursday. “It was our finest hour, I would say,” says John Kivlehan, Transit’s head of buses.

Every hour, from three central points in Brooklyn, 350 buses took commuters over the Manhattan and Williamsburg Bridges up First Avenue to Midtown and then, at evening rush hour, back. The bus bridge highlights both the flexibility of buses and the subway’s carrying power: 70 people on a B61 bus don’t come close to the 1,500 or so you can get on one A train. Bus service was mostly restored by Tuesday, 1,100 buses on their routes; about 1,000 bus staff stayed on cots in more than two dozen bus depots and anywhere else they could find room. To make the bus bridge, those 350 buses were pulled from service elsewhere. The governor waived bus fares, for easy on and off — or “load and go,” in transit parlance.

The police jumped in after the first morning to help with traffic, maintaining bus-only bridge lanes, a transit planners’ dream come true. (The Select Bus Service on First and Second Avenue, or older similar arrangements in many South American cities, offer examples of how well bus service can work in cities.) “I really think it showed that when you dedicate lanes, when there is a fixed guideway for us, we can move so much faster,” Kivlehan says.

The bus bridge got the M.T.A. to the weekend, when the test runs on the under-river tunnels were being completed. If you were at the scene of the long but moving lines at the Barclays Center or Borough Hall in Brooklyn, you heard people complaining, but not that much. It was one of those rare moments in New York when people acknowledged that transit workers were working hard. “I mean, you’ve got to recognize some of these people lost their homes in these storms,” Kivlehan says. “I met an operator out in Far Rockaway who was operating our A shuttle, which replaced our train in Far Rockaway. She was helping a passenger. Quite frankly, the passenger’s MetroCard didn’t work, and the woman was crying. And I watched the operator walk over to the A.T.M. and take out 20 bucks herself, so the lady could buy a MetroCard. I was thanking the operator later, for the service she was giving, and she told me she hadn’t been home, that her home was wiped out.”

‘WE HAVE TO WORK WITH WHAT WE HAVE’

When the next hurricane is headed toward New York City, some differences in subway preparations will be noticeable, but most will not. Maybe you will see a new, stronger, plastic replacement for plywood. You will see a few new-style vent and entrance covers. But you might not see too many futuristic gadgets. “We have to work with what we have,” says George Deodatis, a professor in the Columbia University Department of Civil Engineering, who was an author of a 2011 New York State-sponsored report on the effect climate change will have on the region’s economy and infrastructure. “I remember [the M.T.A.] saying that if we are going to completely strengthen the system, then we will have to stop running the system,” Deodatis says. But it could be strengthened piecemeal, and Deodatis can’t understand why the M.T.A. opened the South Ferry station so recently without a floodgate of some kind. “To me, this is still a huge question.”

Transit officials are thinking hard about long-term accommodations. “We are looking at tunnel plugs, dams, watertight doors — submarine doors, people call them,” says John O’Grady, the M.T.A.’s engineer in charge of capital investment. “We are looking at erectable, scaled, closure mechanisms. We are looking at things called tiger dams, and tiger dams are essentially large bladders that are filled with water and anchored to the ground in front of a component, and they provide at least a temporary blockage from flooding.” The authority is surveying transit systems around the world that have canopied entrances and retractable gates, that have ventilators and fans elevated on towers, like snorkels.

Perhaps you have already noticed the completely rebuilt sea wall alongside the A-line segment (also rebuilt) that crosses Jamaica Bay, but something you most likely have not noticed are the new pump trains the M.T.A. spent the summer building. Also invisible will be the stormproofing work done underground. Some ducts carrying electrical cables from under-the-street Con Ed power stations to the subway ventilation fans for the Clark Street tunnel brought in enough water to flood the 2 and 3 lines. “Water just poured in through the ducts,” Frank Jezycki says. Everything is connected at the city’s roots, and little things become big when disastrous flooding hits, one big lesson the M.T.A. learned from Sandy.

But mostly you will see plywood and tarps and sand bags, because where they worked, they worked, just the way the old pumps powered by compressed air did. These things saved the Lexington Avenue line, for instance, making it the first line restored to service and enabling the entire system to get back up and running much sooner than it otherwise would have.

The most important thing you won’t be able to see in the next hurricane is the experience that a disaster brings with it. It is not as eye-catching as an experimental tunnel balloon, but Sandy showed that experience is the system’s most vital asset, the experience of people who knew how to deal with the giant pumping and breathing and excreting 660-mile-long passenger-rail system that shuttles a fleet of underground trains a cumulative 341 million miles a year. If a storm bigger than Sandy comes, nobody knows for sure what will happen, even with Slosh maps. But the M.T.A. will draw on the experience of those who have been through some version of it before.

Tom Calandrella, for instance, who is 40, got into transit just after graduating from St. John’s University in Queens, working on the construction of Bergen County’s light rail before coming to New York City Transit. Calandrella does not expect everyone to think about the system the way he does; his Facebook page has described him as employed by “an undisclosed, publicly reviled state agency.” “The thousand positive experiences do not equal one negative experience, and that’s the problem with operations,” he says.

He ran the R.C.C. during Sandy, and has somewhat reorganized the place since, including adding a new meeting room — when the governor showed up, they didn’t have anywhere to put him. “My father was a track worker in the ’70s,” Calandrella says. “He remembers as a track worker one of his first tasks was to go and pull every third spike out of the system to go reuse elsewhere because they weren’t buying new railroad spikes. So we were cannibalizing parts of the system to use in other parts of the system. It was almost a siege mentality back then, it was so bad, the system was in such disrepair. One mainline derailment a week. It was almost like Hurricane Sandy for six years.”

Longtime transit employees like to say that in the ’70s, when transit had very little financing, the Stock Exchange didn’t open some days because the subway couldn’t get the workers to the floor. Back then, as after Sandy, what kept the system going was the passion of beleaguered employees — train nerds, really.

“There is a hypothetical R.C.I. in the field today,” Calandrella says, referring to a road car inspector, “who remembers having to fix five trains a day at each station in one location. There is not somebody with five years of experience who knows how to do that.”