Watching over some of the finer things, the guards at the National Gallery of Art stand in dignified silence in crisp, white shirts, navy trousers and police hats. They lean against the portals of the tall, skylit chambers of white marble, and they joke as they spell one another at the changing of the guard, saying, "It won't be long now."

Michael Butler spends some of the time thinking about the painters and the people who pass by him in a genteel stream, greeting those who enter his gallery with a quiet "Hi." He's a security guard whose workweek includes weekends, when most people are playing.

"When I see other people out on Saturdays and Sundays," he says, "I know what they are having -- a good time. You sacrifice that weekend, so I look at it as maybe I'm doing somebody a favor: If we all had weekends off, there would be a lot of people who wouldn't enjoy themselves. There wouldn't be any movies on Saturday afternoons."

Butler, a 33-year-old bachelor, has worked at the Gallery for almost a year. Security is a career to him. He's worked for hotels, been a private investigator and an army recruit. "My first tour of guard duty, I was put in a bank; they gave me an M-16, and I've loved it ever since."

At the National, guards are assigned a daily rotation of four galleries -- the rooms where people come and go, talking of Michelangelo: men in rubber-soled shoes, squeaking as they walk; women speaking softly in German as they alight on a brown sofa, one by one, like birds, then depart in a flock; and some people just sitting alone and staring for long moments into one painting.

Butler likes one American painting so well that he carries the name with him on a slip of paper to remember it: "Morning in the Tropics" by Frederic Edwin Church. It's an idyllic landscape that hangs in gallery 67. "I can stand in that gallery," says Butler, "and if there's no one around, it's like being there. It's like paradise. That's something I couldn't get from any other job."

In the foreground of the Church painting, a pair of red-breasted birds perch on a palm. The jungle fades into muggy air; sunlight glistens through the mist. You could get lost in it.

"A lady came up to me," says Butler, "and asked me about this painting. I had to explain to her it seemed to be a place where there was no one else around. I could stand there and picture myself being there.

"Then she asked me, has anyone ever passed through I would like to carry to that place? For a while, it just shot by me, until she started to walk away, and I said, 'Huh?' "I guess I'm a little slow in picking up these things."

Then there are the children who are less enthusiastic than their parents: "They'll get tired and bored, and they'll sit around and pout," says Butler. Sometimes, to rebel, a kid will reach up and rub a picture frame when the parents turn away. Says Butler, "The kid touches it in my presence, when I am looking, as if to say, 'This guy will really get things moving.' So I'll go over and talk to the parents.

"The kid does this in order to get the parents to say, 'I gotta take the kid out of here.'" Butler likes Dutch and French paintings, especially post-Impressionists. "Monet -- I like the things that he does with landscaping, a bridge or some water. Rembrandt I like for the varied detail. Of course now, Picasso I'm fascinated with, and it leaves me wondering: What was this guy really thinking? Same with Van Gogh; I understand there was some mental problem.

"For instance, you get up close to it, that's one thing. When you stand back you get an entirely different picture. What inspired this guy to create such a masterpiece?

"One time I was standing there. I said, I should try my hand at painting. Maybe I can come up with the perfect masterpiece. Then I said, no, that's not for me. Rembrandt found his, and I found mine. I'm totally involved in security -- whether at the National Gallery of Art or at some other job. That's the profession I would choose."

Protecting the family jewels of the Smithsonian produces its strains. "There's sometimes I get tensed up," says Butler. "When you've been in security for a long time, you get tensed up.

"Some people tour, have a nice time. Then you have to wonder -- when is that nut coming through? The guy who might slash a painting or the guy who might leave a package on the sofa that's not a friendly-type package? "There are times when I leave work not relaxed. I like jazz. I have invested in a stereo system. I put the headphones on and just relax."

On Butler's weekend, which falls on Wednesday and Thursday, he may go jogging in the morning or play a little tennis. He usually has lunch with a woman friend at the Sheraton-Carlton or at Trader Vic's. He talks shop: "Being infatuated with security-type projects, I go to trade shows and look at locking devices," says Butler. "I like to look at it; I don't plan to buy it." Reflecting this interest is his current reading -- books on training canines and protecting executives.

When Butler goes out for dinner, he looks for seafood: He'll eat at the Red Lobster, where, he says, "They have this favorite drink of mine, strawberry daiquiri, and they seem to be the only ones who know how to make it." He likes Market Inn and Hogate's, too.

Most of the movies he's seen lately he describes as "junky," but one he did like was "Missing." He doesn't get to the theater as much as he wants: The last show he saw was "For Colored Girls Who Have Considered Suicide When the Rainbow Is Enuf," which was here five years ago.

A favorite haunt around town is Lafayette Park, where he likes to sit on warm days. And, says Butler, "Believe it or not, when the weather's bad, occasionally you find me browsing through one of the museums. There's nothing like it. The Smithsonian, I can go through it and identify with these guys on guard duty: 'I've got a job just like that, buddy.'"