[3] Davis contributed one composition ("Agitation", which the quintet would often play live,[4] as they did at the Plugged Nickel dates later that year), and co-wrote two pieces with Carter ("Eighty-One" and "Mood").

[7] Hancock recalled how Davis approached "Eighty-One": "Miles took the first two bars of melody notes and squished them together, and he took out other areas to leave a big space that only the rhythm section would play.

The trumpeter was in superb form, able to execute quickstep swing at fleet tempi with volatile penetration, to put the weight of his sound on mood pieces, to rear his way up through the blues with a fusion of bittersweet joy and what Martin Williams termed 'communal anguish.'

Wayne Shorter's ease with indeterminate melodies and his eagerness to join the rhythm section in churning up the music to the point that it threatened to break loose from the traditions of jazz gave Davis the space he needed to reexamine his own playing.

"[7] In a review for AllMusic, Stephen Thomas Erlewine commented: "ESP marks the beginning of a revitalization for Miles Davis, as his second classic quintet... gels, establishing what would become their signature adventurous hard bop.

'Eighty-One' has a strong backbeat, and the kind of regular, repetitive bass line and percussion that was characteristic of funk, and still considered somewhat infra dig in jazz.

Any suggestion that Miles only began to explore a rock idiom on 1970's Bitches Brew misses the mark by a good four years.