Time for action—breaking down Imagine by John Lennon

Let's have a look at each section of this seminal work by John Lennon. You can find a video of the song at http://www.youtube.com/watch?v=-b7qaSxuZUg if you don't have it already. This song is extremely simple in terms of arrangement, but nonetheless, is a powerful piece of music. The verses and choruses come in two parts, so when we see divisions like 1a and 1b, we are simply stating where the section changes a bit:

1. Piano Intro: This is four bars long, based on the verse. It's only piano.
2. Verse 1a: It is eight bars long - Imagine there's no heaven... Lennon describes an imaginary world different from our own. It has piano and Lennon singing.
3. Verse 1b: This is four bars long - Imagine all the people... Lennon alludes to the happiness of the people that live in this world. Drums enter with the bass, piano, and Lennon singing.
4. Verse 2a: This is eight bars long - Imagine there's no countries... Lennon describes...