(c) 2009, The Washington Post The first lady stepped off Air Force One during the Obama family's recent mini-vacation out West wearing a pair of moss-colored shorts. They were not the kind of knee-grazing Bermudas or pedal pushers that the fashion industry has long advocated as work-appropriate sportswear during the summer months. They were not tailored, nor were they masquerading as a skirt. Michelle Obama was wearing play shorts -- the kind of casual cotton fare that a woman might choose for a family outing when her itinerary includes hiking around the rim of the Grand Canyon on a hot summer day, which is precisely what the first lady was going to do. Obama, who joined the president and their two daughters for an excursion to the national park, looked like any other American tourist. Indeed, many sad-sack sightseers could take a few lessons from her style. The shorts fit her figure; she was not wearing a souvenir top that read: 'My family went to Washington and all I got was this lousy T-shirt.' She was not sporting a fanny pack. Or wearing beaten-up rubber flip-flops. She looked fine. But that doesn't make the ensemble OK. The noteworthy aspect of Obama's ensemble is that in recent history, first ladies have rarely dressed so informally in public, particularly as they are emerging from Air Force One while a phalanx of photographers stands ready to record the moment. This exclusive group of women might have dressed in a relaxed manner -- khakis or jeans, for instance -- but it was always in a way that suggested that they were keenly aware of the ever-present cameras. None of them revealed as much leg as the current first lady, either -- a fact that has been duly noted on the Internet by a nation that gets more squeamish about an artfully photographed nude than it does over a naked body lying in a pool of fake blood on an episode of 'Law & Order.' Of course, none of the other recent first ladies was an avid fitness buff. Magazine articles were not dedicated to speculation about their workout routines. Obama's thigh-skimming shorts speak to body confidence and athleticism rather than fashion, sex appeal or coquettishness. The first lady, after all, was wearing trail shoes with her shorts, not gladiator sandals. The image of Obama in her shorts was strikingly modern. And for a long time, modern was not a word typically associated with the role of first lady. The women who have most recently occupied that nebulous position often seemed terribly constrained by its traditions, by the contradictory demands of the public, by the desire to do the nation proud and by the need to live a fulfilling and authentic life. Balancing all that is impossible, and so these women have cherry-picked some things that are inviolable and gone on from there. The public has been free to applaud or criticize each woman's choices. The resulting analysis has had first ladies declared, among other things: elitist, dowdy and tragic victims of chauvinism. Bringing up the subject of the current first lady's shorts -- indeed even admitting to noticing them -- already has people booting up their laptops and taking big, gulping swigs of self-righteousness before firing off e-mails and tweets declaring the whole discussion pointless. But until the West Wing -- and not the East -- starts regularly fielding inquiries regarding china patterns, decorators and the menu for upcoming White House dinners and luncheons, the first lady will be burdened with matters of aesthetics. And her person remains the primary device in communicating her philosophy. In this case, Obama has espoused an aesthetic rooted in realism and inclusion, as evidenced by a White House that embraces poetry jams, country music and classical technique, as well as formal dinners that get funky with Earth, Wind & Fire. Fashion can be an indispensable tool for delivering a message about approachability and empathy. But that doesn't mean it would be a good idea for the first lady to wear a pink velour Juicy Couture track suit when she travels, no matter how real and modern and comfortable it might be. No matter that so many other women of her generation choose travel clothes that mimic pajamas. When the first couple disembarks from Air Force One, military personnel stand at attention, shutters click and minions scurry. It's not as though they are climbing out of their own personal RV with their backpacks -- like celebrities caught unawares by the paparazzi. Ultimately, the first lady can't be -- nor should she be -- just like everyone else. Hers is a life of responsibilities and privileges. She gets the fancy jet. She has to dress for the ride. (Optional trim begins here) Unlike the president, whose entire life, down to his medical history, is available for public scrutiny, or the first children, whose lives are almost entirely private, the first lady lives in a constant tug-of-war between the private and the public. Her private family vacation might have called for sport shorts. Her very public descent from Air Force One would have been less jarring -- what with two stern servicemen standing ramrod-straight and the bulletproof presidential 'beast' waiting -- if her attire had been more polished. Was a suit required? A fancy dress? Or any kind of dress, for that matter? Absolutely not. This is 2009, after all, not 1950. But there's a difference between shorts that could be worn jogging and those that one might wear to a backyard barbecue. Or at least that's as it should be. The reality is that a good portion of the culture has become loudly vocal about how clothes don't matter and how it's snobbish or shallow to suggest that they do. But clothes are part of our broader aesthetic obligation to each other. That commitment pushes homeowners to mow their lawns and not be a blight to the neighborhood. It makes them think twice before painting their houses in psychedelic stripes. The desire to be aesthetically respectful means guests give consideration to what they wear to a friend's wedding or mourners take care in how they dress for a loved one's funeral. In the White House, the aesthetic demands are higher than they are on Main Street. There are no neat rules, only confounding expectations. First ladies often get caught up in a desire not to appear elitist -- the lingering aftermath of Nancy Reagan's painful lessons in ready-to-wear borrowing. But few observers seem to remember that Rosalynn Carter took her share of criticism for wearing a recycled dress to her husband's inauguration. How miserly!, critics clucked. (Optional trim ends here) Avoiding the appearance of queenly behavior is politically wise. But it does American culture no favors if a first lady tries so hard to be average that she winds up looking common. 