Maxwell's Silver Hammer

"Maxwell's Silver Hammer" is a song by The Beatles, from the Abbey Road album. Paul McCartney sings lead vocals. It was written by McCartney, though the songwriting credit is Lennon/McCartney.
Structure
The vaudevillian-style song is about medical student Maxwell Edison, who uses his silver hammer to murder his girlfriend Joan, then his teacher, and finally the judge during his murder trial. Despite the grim subject matter, the song is bouncy and upbeat (a "happy song about a serial killer").
Meaning
McCartney said in 1994 that it symbolizes the failures of life:
"Maxwell's Silver Hammer" is my analogy for when something goes wrong out of the blue, as it so often does, as I was beginning to find out at that time in my life. I wanted something symbolic of that, so to me it was some fictitious character called Maxwell with a silver hammer. I don't know why it was silver, it just sounded better than Maxwell's hammer. It was needed for scanning. We still use that expression now when something unexpected happens."
McCartney referred to the song when talking about his 2005 album Chaos and Creation in the Backyard:
"In the past I may have written tongue-in-cheek, like 'Maxwell's Silver Hammer', and dealt with matters of fate in a kind of comical, parody manner. It just so happens in this batch of songs I would look at these subjects and thought it was good for writing. If it's good enough to take to your psychiatrist, it's good enough to make a song of."
Recording
After resuming to record the Abbey Road album, the Beatles began recording Maxwell's Silver Hammer at Abbey Road Studios on 9 July 1969. McCartney, Harrison and Starr taped 16 takes of the song, followed by a series of guitar overdubs.
The following two days the group overdubbed vocals, piano, Hammond organ, anvil and guitar. The song was completed on 6 August, when McCartney recorded a solo on a Moog synthesizer.
John Lennon later said, "I hate it....He did everything to make it into a single, and it never was and it never could have been."
George Harrison described it in 1969 as "one of those instant whistle-along tunes which some people hate, and other people really like. It's a fun song, but it's kind of a drag because Maxwell keeps on destroying everyone like his girlfriend then the school teacher, and then, finally, the judge." In 1977 Harrison was more candid, describing it as "so fruity" but added "we did a good job on it".
The length of time it took to record the song created tension between the Beatles. Paul McCartney said: "The only arguments were about things like me spending three days on Maxwell's Silver Hammer. I remember George saying, 'You've taken three days, it's only a song.' - 'Yeah, but I want to get it right. I've got some thoughts on this one.' It was early-days Moog work and it did take a bit of time".
Personnel
Paul McCartney - lead and backing vocal; overdubbed guitar; piano, Moog IIIp
George Harrison - backing vocal, guitar, bass
John Lennon - backing vocal, acoustic guitar
Ringo Starr - backing vocal, drums
Mal Evans - anvil
George Martin - organ
Personnel per Ian MacDonald, Andy Babiuk and Mark Lewisohn
For the studio version of the song, the anvil was played by Starr; in the Beatles film Let It Be, however, Mal Evans is seen hitting the anvil as the Beatles play the track.