The 100-year anniversary of the birth of Greta Garbo (nee Gustafsson) on September 18 has been celebrated with two new biographies, a DVD collection, a television documentary, a traveling portrait exhibit, and even a U.S. postage stamp. It is a fitting tribute; her beauty has been universally adored. But what of her impact on style?

Many Golden Age Hollywood stars made their fashion mark modeling clothes by designers like Edith Head, Givenchy, or Adrian. Joan Crawford’s ankle-strap shoes and exaggerated shoulder pads sparked popular trends. But none of Garbo’s film costumes translated into mass-market imitations. Her strongest fashion influence stemmed from how she dressed in order to avoid the spotlight after retiring from films.

She last appeared on screen in 1941 at the age of 36, and she followed this early retirement with decades of rebellion against conventional celebrity: she covered herself in cloaks, sunglasses, and hats. While other actresses of the era would not so much as fetch a newspaper from their driveway unless they were dripping in jewels, she was determined to step into the street and into society as a free woman, not a star. Often branded a recluse, Garbo has been more accurately described as a recluse about town. Wearing hats with enormous brims and huge sunglasses to hide her face, she frequently took long walks through Manhattan, where she lived the last half of her life on East 52nd Street. And whenever a lucky photographer managed to get close enough for a decent candid, Garbo responded with her classic, defensive gesture. She would raise her hand or cloak to hide her mouth, the one feature she thought most belied her age, at just the right moment to ruin the shot. Even in one of the last known pictures, on her way to the hospital, she was not so weak that she didn’t raise her hand and cover her face one final time.

The rare photos of the ambushed actress on her city jaunts captured and disseminated the style that has since become known as vintage Garbo. Simultaneously grabbing and frustrating our attention, the conspicuous hats added mystery to the woman hidden underneath, an inscrutability that only inflated the celebrity she ostensibly wanted to shake. Beauty obscured became beauty imagined – and legend sustained.

Although many celebrities have co-opted the look since, most notably Jacqueline Kennedy Onassis, Garbo did “incognito chic” first. What elevates Garbo’s execution of the look above those who copied her was an unswerving dedication to the privacy the look protected, the human freedom it asserted – the freedom to just be. Her rejection of any and all public attention validated and confirmed the principles underlying her aesthetic. In the half-century before her death in 1990 at age 84, she never made another movie, never wrote her memoirs, never chaired social or charity events, never endorsed products, never answered fan mail, and certainly never granted any interviews. She demanded similar discretion from her friends, who were immediately and permanently banished from her life if they spoke about her in public. Who else can claim such thorough authenticity?

The aggressively private side of Garbo’s life is an essential component of her well-deserved legend, but it was her face that enthralled the public long before she turned away from her fame with such grand style. If, as theorist Roland Barthes wrote in “Mythologies,” “the Face of Garbo is an Idea,” then each of us “thinks” Garbo differently. “Just make your face a blank,” director Rouben Mamoulian advised the star on the set of 1934’s “Queen Christina,” and “let each man and woman write on it” for themselves. In the film’s tragic final scene, her wide and luminous eyes stare out at sea from a face whose perfect and motionless surface is a canvas upon which we paint our own feelings.

It’s true that Garbo did just want to be left alone, but her intense secrecy and undercover look achieved something that transcended her own personal entitlement to independence. By reclaiming Greta Gustafsson for herself, she preserved Greta Garbo for the world. Precisely because she unreservedly gave us her flawless, haunting face for a moment, and then later held it close, Garbo – ageless visage, eternal idea – will be Garbo forever.