"Tomorrow Never Knows"
Two instruments provide the underlying harmony of the song: the tambura and the bass guitar. The tambura establishes an unchanging tonal foundation, its constant C drone sustaining a hypnotic backdrop that anchors the shifting textures and loops while evoking the atmosphere of Indian classical music. By refusing harmonic movement, the tambura creates a sense of stasis at the heart of the track and magnifies the impact of even the smallest inflections elsewhere in the arrangement.
Against this drone, McCartney’s bass supplies the core of the groove, similar in function to his line in “Taxman.” He alternates between straight and syncopated rhythms within the measure, mirroring the half-measure symmetry of Starr’s drum part. In the first half of the measure, McCartney outlines octaves of C in a steady stream of eighth notes. The notes are intentionally sustained and overlapped, requiring multiple fingers to fret the octaves, and his use of a pick rather than fingerstyle adds a sharper attack that allows the sustained tones to blur together while retaining clarity.
The second half of the measure turns toward syncopation. While the repeated C notes on the “and” of two and beat three lock tightly with the kick drum, McCartney introduces variation by leaping to the flat seventh (B♭) on the “and” of three, firmly situating the line in C Mixolydian. He follows this with the upper octave of C on the “and” of four, a note that sustains into the downbeat of the next measure. This overlap blurs the barline, reinforcing the looping, trance-like quality of the groove.
Like Starr’s drum pattern, McCartney’s bass line never changes, even during the brief harmonic shift to Bb/C (bVII/I) suggested by the organ. Together with the tambura’s drone, it locks the song into a cyclical framework where the sense of motion arises less from harmonic progression than from timbral layering and textural transformation.