Jack Valenti (search) created the movie-ratings system. He's been Hollywood's ambassador to Washington since 1966. He's become a vigilant policeman on film piracy.

Yet what was his greatest achievement as head of the Motion Picture Association of America (search), a job he is leaving after 38 years?

"I survived," Valenti, 82, wrote in an opinion column in Monday's Los Angeles Times.

"To endure in a volatile, unpredictable arena populated by egos the size of small planets is not an inconsiderable achievement," Valenti wrote.

Valenti noted the vast changes in Hollywood during his tenure: the decline of studios run by pioneering movie moguls in favor of corporate-owned production shops; huge increases in production and marketing costs; reliance on make-or-break opening weekends; the growth in the international box office; the explosion of the DVD market; and the piracy risk digital cinema presents.

"Yet one thing has not changed," Valenti wrote. "A moviemaker's single indispensable asset -- as elementally essential now as it was in the Golden Years -- is the Story. And that means studio executives of this era must share the same DNA as industry pioneers in at least one particular -- the ability to find a narrative with heart and heat."

Dan Glickman (search), former U.S. agriculture secretary under President Clinton, takes over as MPAA head Sept. 1. Valenti will continue to oversee the movie-ratings system.