In 1958, guitarist Jim Hall, in notes to a Jimmy Giuffre record, used the term "instant composition" to describe improvising. A few years later, Misha Mengelberg, knowing nothing of this, recoined the term, and it stuck. A quiet manifesto, those two English words countered notions that improvising was either a lesser order of music-making than composing, or an art without a memory, existing only in the moment, unmindful of form. Misha's formulation posited improvisation as formal composition's equal (if not its superior, being faster).
Yes but: Misha says he was thinking of "instant coffee," stuff any serious java drinker (count Misha in: espresso cup rattling in its saucer announces his approach to a stage) recognized as a sham substitute, however aggressively sold