From
Rubber Soul. A confluence of several
Beatles things. Acoustic folkiness, this still being
John Lennon's
Bob Dylan phase. A
sitar part (and other exotica, in some mixes), from student
George Harrison. Double-tracking of vocals, from the early part of the band's
studio experimentation (later to lead to the hermetically-sealed aural
Goon Show of subsequent recordings).
Infidelity, as Lennon decides his first marriage wasn't
all that.
Norwegian Wood