Aquarius/Let the Sunshine In

The genius of this arrangement lies in the contrast between its two halves. The Aquarius section uses descending Aeolian minor progressions to create a mystical, floating atmosphere, while Let the Sunshine In shifts to a simple major-key gospel vamp that builds through vocal dynamics rather than harmonic complexity. The parallel major modulation from E minor to E major is the arrangement's most powerful harmonic moment, transforming introspective prophecy into communal ecstasy. Bones Howe's orchestration layers strings and brass over the Wrecking Crew's rhythmic foundation, adding a jazz-inflected sophistication characteristic of the sunshine pop genre. The medley structure itself, combining two songs in different keys and moods, was harmonically innovative for a pop single.

"Aquarius" and "The Flesh Failures (Let the Sunshine In)" were written as separate songs for the rock musical Hair. Galt MacDermot composed the music while Gerome Ragni and James Rado wrote the lyrics. Hair debuted Off-Broadway in late 1967 before transferring to Broadway in April 1968, where it became a cultural phenomenon exploring the hippie counterculture, sexual revolution, and anti-Vietnam War sentiment. Producer Bones Howe conceived the idea of fusing the two songs into a single medley for The 5th Dimension, creating the dramatic arc from mystical prophecy to ecstatic gospel release that defined the final recording.

The 5th Dimension transformed two songs from the Broadway musical Hair into a seamless pop-soul medley that topped the Billboard Hot 100 for six weeks in 1969. Produced by Bones Howe with legendary Wrecking Crew session musicians, the track bridges mystical folk-pop and ecstatic gospel into one of the most recognizable recordings of the entire decade.