Recorded in June 1965, McCartney said he work up with the tune from "Yesterday" in his head. He wonders where the thoughts come from- but adds: “You don’t ask yourself too much or it might go away….. It is the most instinctive songs I’ve every written."
Lennon remarked how he thought the lyrics don’t resolve into any sense:
"They’re good- but if you read the whole song- it doesn’t say anything you don’t know what happened. She left and he wishes it were yesterday- that much you get- but it doesn’t really resolve"
He added: “Well one, beautiful- and I never wished I’d written it.”
John Lennon referenced this song in his anti-McCartney solo effort "How Do You Sleep?" with the lyrics, ''The only thing you've done was yesterday, and since you've gone you're just another day."
All three Beatles agreed there was no instruments they could play on the song- so it ended up being the first Beatles song with just one of them on it. It was number one for four weeks in the UK.
The Beatles were one of the first (if not the first) of the modern rock era. Their style brought a whole new perspective into modern music. The track steps back and lets the music play softly. When performing it, only the right chords in the right position are allowed because chords cadence is perfectly connected with melody. This may explain why the song can be considered as a little work of art in pop music.
It was the first Beatles song to capture a mass adult market. Most of their fans were young people to this point, but this song gave the band a great deal of credibility among the older crowd. It also became one of their "Muzak" classics, as companies recorded instrumental versions as soothing background noise for shopping centers and elevators. It “mainstreamed” them.
During recording, loudspeakers were used to cue the string quartet and some of MCartney’s voice was recorded onto the string track which can be heard on the final recording.
Putting the song into perspective, Beatle scholar Alan Pollack writes:
"As is often the case with the over-exposed war horses of any artsy genre, whether or not you "like" this song, there's some good reason why it became so over-exposed in the first place. It's a fine piece of work with something going for it in virtually every department: the unique arrangement, an attractive tune, even some asymmetrical phrasing and a couple of off-beat chord progressions. By the same token, one should not be fooled by whatever unique and interesting factors surround the song's history and production into thinking of it as more unique and different than it is."