From Rolling Stone:
The B side of “Paperback Writer” was this blurry, aggressive song: Lennon’s response to people moaning about the wet British weather. It featured one of the earliest uses of backward tape, which Lennon said was the result of being stoned and accidentally spooling up the tape wrong. It also included a virtuoso performance from Ringo Starr. “I feel as though that was someone else playing,” he said. “I was possessed!”
The inspiration for “Rain” is agreed on by Neil Aspinall, the Beatles’ roadie, and John Lennon. They both described the band’s arrival in Australia, marked by rain and poor weather. Lennon said, “I’ve never seen rain as hard as that, except in Tahiti“, and later explained that “Rain” was “about people moaning about the weather all the time.”
While technologically elaborate, “Rain” has a simple musical structure. Set in the key of G major, it begins with what Alan W. Pollack calls, “a ra-ta-tat half-measure’s fanfare of solo snare drums“, followed by a guitar intro of the first chord. The verses are nine measures long, and the song is in 4/4 time. Each verse is based on the G, C, and D chords (I, IV, and V). The refrain contains only I and IV chords, and is twelve measures long (the repetition of a six-measure pattern). The first two measures are the G chord. The third and fourth measures are the C chord. The third measure has the C chord in the so-called 6/4 (second) inversion. The fifth and sixth measures return to the G chord. The refrain, though seemingly slower than the verse, is at the same tempo. Pollack says this illusion is achieved by “the change of beat for the first four measures from its erstwhile bounce to something more plodding and regular”. After four verses and two refrains, a short solo for guitar and drums is played, with complete silence for one beat. What is heard next is what Pollack calls “historically significant” reverse lyrics.
“Rain,” the B-side of “Paperback Writer,” was like its companion a sonic groundbreaker for the Beatles, although lacking the kind of melodic hooks that made the A-side a number one tune. The tempo seemed almost deliberately sluggish, just this side of a dirge, while the guitar textures seemed deliberately blurry. John Lennon delivered the sing-melody with a laconic nonchalance, although (as on “Paperback Writer”) the Beatles sang high counterpoint harmonies that recalled the Beach Boys and greatly enhanced the attractiveness of the tune. In hindsight — and maybe even at the time, for those in the know — this apparent out-of-focus sluggishness seemed motivated by the hallucinogenic drug experience, with changes in sensory input and perception resulting in altered states and temporal elasticity. Whether the attempt to reflect that experience in song was intentional or not, the track’s hazy textures were certainly successful in doing so. The Beatles had only just recently…begun to write songs that dove into subjects that had nothing to do with man-woman relationships. “Rain” was their first effort…in which the words were not just about different subjects, but downright enigmatic. On the surface, it was a very English observational song, to the point of banality in some respects, about being in the rain and people sipping their lemonade. On a deeper level, it could be heard as an embrace of the drug experience, or of any experience in general that wallowed in sensation and reverie. Certainly the Beatles don’t seem to mind getting wet, as the chorus emphasizes: rain (or sunshine for that matter), they don’t mind, the weather always seems to be fine. Words aside, the instrumental track featured some very imaginative touches, particularly McCartney’s bulging bass and Ringo Starr’s creative drum breaks (especially when he kicks the track into gear again after a brief false ending). The wildest effect is saved for last: the instrumental fade is dominated by one of the first uses of backwards vocals in a pop recording, in a gentle swirl that reinforces the suspicion that the song’s inspiration was partially chemically derived.