"Gary's Notebook" is a minor-key blues original by Lee Morgan from his 1963 Blue Note album The Sidewinder. Set as a 12-bar blues in B-flat minor at approximately 178 bpm, the tune brings a dark, sophisticated harmonic palette to the blues form. Tenor saxophonist Joe Henderson opens the solo section with three choruses that showcase his gift for building intensity gradually, his angular lines navigating the minor-key changes with characteristic inventiveness. Morgan follows with three trumpet choruses of hard-swinging brilliance, his melodic ideas flowing with the rhythmic confidence that made him one of hard bop's most exciting improvisers. Pianist Barry Harris closes with three choruses that demonstrate his encyclopedic command of the bebop tradition. The minor blues setting provides a harmonic environment that is both familiar and challenging, pushing the soloists beyond the standard major-key blues vocabulary into more adventurous territory. Within the context of The Sidewinder album, this track represents the more straight-ahead, hard bop side of Morgan's musical personality, balancing the album's commercial funk appeal with uncompromising jazz substance. The performance exemplifies the high standard of improvisation that defined Blue Note's output in the early 1960s.