He just reached under the table and flicked the switches, so now all the lights in the Victorian village are up, the crossing signals are flickering, the Lilliputian yardman is going in and out of his gatehouse, the hobos down at Hobo Curve are squatting over their teeny-teeny fire (you can just make out the flame's reflection in their haggard faces), the bundled ice skaters at the town pond look ready to negotiate figure 8's and -- best of all -- the six trains, including the trolleys, are all going at once: tooting and whistling and smoking and rattling and banging and highballing and otherwise electrifying you back to some far place you thought you'd left behind. Was it the toy department at Marshall Field that Christmas it turned 20 below all over the Midwest? Was it the basement of that rich and gabby uncle your mother never could stand? Never mind. You're back, back like that, back in split-second childhood Christmas dreamtime, and all it took was for a man named Hezekiah ben Aaron to flick the switch on his gorgeous and humongous model train display in the West Hall of Union Station.

Today, 24 days till the Big Day, there'll be thousands standing in the West Hall, conveyed back home.

Hezekiah ben Aaron used to be the train consultant at FAO Schwarz on Fifth Avenue in New York City. He started out there as a stock boy. In his own way, he's a model railroader legend, especially in the jumbo-sized "G" gauge, which is what this layout is. Now Hezekiah ben Aaron is Washington's Trainman, at least for this holiday season, wizard of a 16-by-32-foot layout that's at a scale of 1:22.5, which is to say only 22 times as small as real life.

Hezekiah ben Aaron doesn't own this fantasy -- he just designed and wired it. The layout is the property of the management of Union Station, and this is the third season it's been up and running as a Christmastime gift to the community. (Also a lure to the Union Station shops, of course.) It's hard to say who gets the bigger kick out of it -- parents or their children. Somewhere in the vicinity of 60,000 people pass through Union Station every day of the year, say the terminal's marketing directors. That figure usually increases during the holidays. An estimated 20,000 of these passing-through adults and kids will be mooning daily between now and New Year's over these glittering strings of electrified boxes as they circle and huff and puff to glory.

The person who makes the glory chug is a 39-year-old self-described born-again Jew. "I may not celebrate Christmas the way Christians do," he says, "but when it comes to toy trains, I figure we're all in the same religion." He adds: "If trains had not been in my childhood, I might not have survived." He happens to mean this literally, because ben Aaron will confide, after you get talking to him, that he was a battered child, and there is no reason at all to disbelieve him.

But why not stick with the fantasy? Or is this a fantasy? Everything is so lifelike here, and for another thing, ben Aaron himself seems to love bending reality a little, toying a bit with your imagination. Take that little pig in that little crate on that little farm wagon over there.

Hezekiah ben Aaron, in striped overalls and cordovan wingtips, is shaking his head, and there seems an absolute consternation in it.

"Somebody forgot about that pig," he says. "He's out there in that freezing snow. Need to get him in for the winter, poor thing."

If you're not a kid, don't apply here.

He points out a freight shed. He's bending over, peering inside. This shed is down a few feet from the freezing pig. "Mmm. They left the doors open to that shed. Must be kind of cold for the guys working in there, don't you think?"

In the window of the offices of the weekly Gazette (it's right down from the hotel and saloon) some clever hand has placed a menorah. "Well, this is a nondenominational layout, it's true," the Trainman explains, "but the editor, you see, is an immigrant from Israel. I mean, why not? He wants to get into the holidays too."

Now he's leading you around to the south side of the display. "Have you found the panda bear yet? No? Okay, then how 'bout the Abominable Snowman? I'm not going to tell you where he is, but I will give you a hint. He's somewhere up there in the trees."

As hints go, this one is stinko, in that there are somewhere between 800 and 1,000 fir and pine trees in this layout. That number doesn't include the blackened trees in and around these seven-foot-high blue Styrofoam mountains. What would a toy-train mountain be without trees scorched here and there by lightning?

"They're made of black coral from the ocean," says the Trainman. "I think we got them from a hobby show. By the way, you just don't go to a toy store. You scour hobby shows, train shows, antique shows -- anyplace you think you might be able to pick up something. Then you customize it."

He is slipping back into reality, such as reality is.

The mountains look a little like the Tetons of Wyoming or the Bighorns of Montana, never mind that this is supposed to be a Currier and Ives scape set somewhere in 19th-century New England.

"Last year we did something nobody caught," he says. "We had seven skiers coming down the mountain. Only thing, six were coming downhill, one was upended in the snow, with his skis pointed heavenward."

Standing over one of the layout's depots, he says, "Those are 50-pound sugar and Idaho potato and Old Mill salt sacks leaning up against the door. There's real grain and salt inside some of them. A doll lady in Pennsylvania made them." A man could rest four or five of these 50-pounders in his palm, imagining he's Gulliver come to life.

One of the houses in the village seems to have just the right look of weathering on its side. "I whitewashed it with vinegar and soap, then painted it with a watered-down yellow," he says.

On the station platform: a billboard for White Pine Floating Fairy Soap. The fine print underneath says: "Have You a Little Fairy in Your House?"

"Detail, detail," explains the Trainman.

So it's all a dream, go with it. At the hobo camp, which is under a trestle, there's the rusted hood of a car, old tires, part of an old newspaper. "The campfire is done with a circuitry design I set up," he says. "It's a little circuit that's shorting, and then isn't shorting. That's how you get the flicker effect."

So saying, ben Aaron reaches under the platform (it's draped with red cloth) and produces a real-life gold-buckled leather maroon briefcase, the kind K Street lawyers like to swing in all their sidewalk-eating self-importance. The Trainman of Union Station opens the case and produces a spare circuit bulb, just in case the hobo fire down at Hobo Curve should go out somewhere between now and Jan. 1, which -- alas -- is the day this whole fantasy is scheduled to go to drabber seasons in some warehouse or other in Northern Virginia.

"These things cost about eight bucks. Basically, I've got this thing wired with super overkill. There's more wiring in this layout than in your average house."

Also in this expensive-looking leather briefcase is an engineer's cap. It's a little mashed. He smooths it out, tries it on. "Ah, now I'm really ready."

He grins. "Basically I'm getting paid to be a kid. What could be better than that? Course, I don't really have much money, it's true."

What he has are the Ten Commandments written in tiny Hebrew script on his watchband. What he has is job contentment, if not job security. (It's a very short season.) He has light blue eyes and a wreath of gray beard; you could almost figure him for Santa Claus. During the off-season, he odd-jobs. He rewires model railroad cars, he consults on private layouts. Basically, he's a man living by his wits.

His dream at Union Station is thought to be the largest portable LGB train layout in the world. (There are some larger permanent displays in the basements of the impossibly rich.) LGB -- Lehmann-Gross-Bahn -- is the German manufacturer of this gauge of train. The main factory is in Nuremberg.

The "S" gauge of our gone childhoods meant only one thing: American Flyer; the "027" was Lionel.

Once, when ben Aaron's funds were really low, he went to work as an Amway distributor and then was about to start working Avon products door to door. But a toy train job came up. In the end, which is to say the beginning, it all comes back to trains.

A man is sipping a cup of coffee in the Station Grill, which is a real-life restaurant about 30 feet from the train display. Actually, the train display has a miniature restaurant in its miniature village, and it also is named the Station Grill. The miniature one was there first. This is getting confusing.

"I don't know if you've noticed, there's no bottom teeth and the top ones are all connected to a plate," he is saying. "It was the beatings.

"I was severely beaten as a child," he says. "I guess you can maybe see that by looking at my face? Lots of people can't believe I'm as young as I am. In one sense I never had a childhood. If it wasn't for the Lord, and of course toy trains, I'd probably be in an institution for the insane now."

Indeed, the more you talk, what you begin to really feel inside a man's exuberance and innocent childlike fantasies is the deeper sadness, the never-to-be-over pain. He abruptly cuts off. "But that's the past. I try not to look back."

Back at the display some handicapped children from Sharpe Health School on 13th Street NW have turned up. They're in wheelchairs. They are cerebral palsy and spina bifida patients. Kenneth Williams Jr., 6, has eyes big as dinner plates.

A 39-year-old man-child in the promised land of toy trainery uncouples one of his cars, brings it over. "Hey, Kenneth," he says, "would you like to hold it?"