In the summer of 1968, a roiling year of war, assassination and political and racial tension, I turned 14 in the Cajun town of Eunice, La. Schools would not fully integrate until a year later, after man walked on the moon. So naïve was I as a boy, so complete and unquestioned was segregation, I thought the sign at the laundromat that said, “Whites Only,” referred to the color of clothing.

In 1968, I was also first drawn irresistibly to the Olympics, an event I have now covered 14 times: Bob Beamon launched a magnificently unbound long jump at the Summer Games in Mexico City. And most startling to a sheltered white teenager in the South, the 200-meter sprinters Tommie Smith and John Carlos raised gloved fists on the medal stand during the playing of “The Star-Spangled Banner” to protest the treatment of black Americans.

Oct. 16 is the 50th anniversary of what is probably the most indelible image of sports activism of the last half-century. It’s the first thing I thought of upon hearing about Nike’s ad campaign with Colin Kaepernick, the quarterback who lost his N.F.L. career after kneeling during the national anthem to protest racial and social injustice.

Kaepernick is a direct activist descendant of Smith and Carlos, unyielding in his conviction, fully understanding of risk and sacrifice and the power and dignity of silent gesture. And he knows something they did not a half-century ago, that history can act as sandpaper, smoothing abrasive denunciation into burnished acceptance.