By 1979, Miles had been absent from the scene for four years. In order not to disappoint his public, Columbia put out unreleased recordings from 1955 (the first quintet) through the winter of 1970. The material focused on 1968, the stunning transitional year, when the second quintet experimented with a new repertoire composed by the trumpeter. At first (winter 1967-68), Miles played around with the electric guitar, but hesitated about the form. In November 1968, he increased the number of keyboards, adding a Hammond organ and two Fender Rhodes that moved as if they were on a dance floor. A new about face took place a year later after the masterpieces of In A Silent Way and Bitches Brew. Miles allowed himself to be tempted by the pastoral mood of David Crosby’s song, “Guinnevere,” with an Indian sitar in the background. But the most fascinating composition was “Circle In The Round” that in November 1967, announced a decisive break in the space of one side of an LP, with thematically repetitive material featuring Tony Williams as the main soloist.