In 1971 George Duke, having just recently done his time with the Mothers of Invention, was engaged by the Cannonball Adderley Quintet. Beginning in April of that year, Duke made two recordings over a short timespan that on their release in 1973 as a double LP (against the desire of the artists, by the way), would be a major statement. On Chapter One of his fusion autobiography, Solus, Duke, along with the skeleton crew of bassist John Heard and drummer Dick Berk, tries out the new compositional philosophy he had absorbed from his work with Adderley. On Chapter two, The Inner Source Duke lives it up as he shows off his exuberant experimental synth side and also begins to vary the line-up here as some tracjs are reinforced with Latin percussion, incisive horn and reed instruments or with Duke on his first instrument, the trombone. As a curiosity, two basses compete with each other on Twenty Five.