It's the theme song for the movie, the title track for the album, and the opening number, and it's a famous song that makes you want to have everything appraised.
The 10th single released in 1965. It reached number one on the Billboard Hot 100 and the UK Singles Chart. The B-side "I'm Down" was later covered by Beastie Boys, Aerosmith, Heart, and others.
This is an up-tempo rock song written for the movie, but it was actually a cry from the heart of John Lennon, who was losing sight of himself in the midst of his growing popularity. The theme of the song is actually "escape from despair."
