Jazz, as Ralph Ellison wrote, “is an art of individual assertion within and against the group.” Each soloist breaks out against the ensemble, and each break enhances both the other players’ individual freedom and the cohesion of the group.

To jam, in other words, is to adhere — a paradox that plays out only in jazz, unless, as the philosopher Terry Eagleton suggests in “The Meaning of Life,” it is also true in love. So it is fitting that on Aug. 12, 1958, the photographer Art Kane called together as many jazz soloists as he could round up for a photograph celebrating the music’s collective moment. In all, 58 musicians (“55 cats and 3 chicks,” as one jazz writer described them) heeded a highly un-jazzlike 10 a.m. call to a stoop at 17 East 126th Street in Harlem, and 57 found their way into Kane’s immortal image. One, Whitney Balliett later wrote in The New Yorker, was “astonished to discover that there were two 10 o’clocks in each day.” The great stride pianist Willie ( the Lion ) Smith, born in 1897, got tired and was sitting on the stoop next door when Kane took his shot.