[David Greenberg, a professor of history and media studies at Rutgers and author of three books of political history, has written the "History Lesson" column since 1998. He is a Fellow at the Woodrow Wilson International Center for Scholars for 2010-11.]

Fifty years ago, on Sept. 26, 1960, John F. Kennedy and Richard Nixon squared off in the first-ever televised general-election presidential debate. Within days, if not hours, the event gave rise to a mythology so well-known by now that it scarcely needs repeating. Handsome, dapper, poised, and articulate, Kennedy dispelled with his appearance any nagging worries that he might be too callow for the presidency. Clammy-faced, awkward, and plagued by his gloomy five-o'clock shadow, Nixon reinforced what he called "the Herblock image," in reference to his nemesis, the Washington Post cartoonist, who had already immortalized Nixon's menacing mug. As the story goes, the winner that night was not just Kennedy but the television image itself, which had, in a single stroke, demonstrated its newfound kingmaking power.

A widely told tale. But it's not quite correct....