How High the Moon

A vehicle for pure improvisation, and Fitzgerald uses it as such — the performance builds from a relatively restrained opening through a series of scat improvisations that transform the song into something between jazz singing and instrumental music. What's astonishing about her voice here is its range in both senses: the physical span of notes she traverses and the emotional range, from playful to ecstatic to almost martial in its precision. The rhythm section drives hard beneath her, and when Fitzgerald leans into the scat passages she matches and then exceeds their intensity. The chord changes (borrowed from "Rose Room") gave bebop instrumentalists a playground, and Fitzgerald colonizes that playground with a completeness that humbles comparison. There's humor in this performance — a lightness that keeps the technical fireworks from becoming intimidating. She invents melodic lines on the spot that would take other musicians weeks to compose, then discards them and invents more. The cultural context is the brief, brilliant era when jazz singing and bebop were genuinely in dialogue, when the human voice was competing with the saxophone on equal terms. This is for anyone who has ever wanted to understand what it means when people say a singer can "play" — Fitzgerald doesn't just interpret this song, she improvises it, making it new each time.