1) The song is significant in the fact that the band thought that it showcased the peak of their performance skills as a band. Ringo has commented since that he rated the song as his best recorded performance ever.
2) For evidence of how tight the band was, listen to the break at 2:35. The interplay between Paul and Ringo is very precise and feels great.
3) Paul's Rickenbacker 4001 bass was recorded using a speaker as a microphone to get a bigger "Motown" style bass sound. The boys had been complaining for a while about how thin the bass on their records was as compared to American records, and this was one of engineer Geoff Emerick's solutions, according to his book "Here, There and Everywhere."
4) The track was also recorded at a faster tempo with the tape machine running fast, which was then slowed down to the correct speed in order to make it sound bigger as well.
5) The interplay between John's chorded rhythm guitar and George's picked rhythm is a thing of beauty. They are played and layered so well that they blend seamlessly together.
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