Once there was Louis Armstrong blowing his beautiful top in the muds of New Orleans; before him the mad musicians who had paraded on official days and broke up their Sousa marches into ragtime. Then there was swing, and Roy Eldridge, vigorous and virile, blasting the horn for everything it had in waves of power and logic and subtlety - leaning into it with glittering eyes and a lovely smile and sending it out broadcast to rock the jazz world.