Miles in the Sky, released in July 1968, only four months after the simmering, beautiful Nefertiti, is another transitional album in almost every respect. The cover art is a psychedelic collage, unlike the moody portraits of Davis that had adorned pretty much every previous release. It also marked the first time electric instruments would appear on a Davis album: keyboardist Herbie Hancock and bassist Ron Carter both plugged in on the opening track, “Stuff,” and guest George Benson played guitar on the second track, “Paraphernalia.” Furthermore, the rhythms drummer Tony Williams plays are based on 4/4 rock beats, rather than the fragmented swing that had made him such a crucial element of the group’s sound to that point.

The album contains only four tracks, but they’re long: “Stuff” runs 17 minutes, “Paraphernalia” nearly 13, “Black Comedy” is a compact 7:31 and closer “Country Son” nudges the 14-minute mark. Davis was back to writing, something he’d avoided on Nefertiti, leaving Shorter, Hancock and Williams to contribute all six compositions; “Stuff” and “Country Son” are his, while “Paraphernalia” comes from the saxophonist and “Black Comedy” from the drummer. But across the board, the complicated melodies and structural challenges of earlier material are gone. These new pieces are built on simple riffs, over which the horn solos are hot and, in Shorter’s case, verge on free jazz at times. But the band spends a lot of time basically vamping in place, something they’d never done before.