Contributed to Lennon/McCartney the song was written by Lennon in 1967 after an argument with his wife at the time, Cynthia Lennon, and, after she had gone to sleep, wrote a line that was repeated through his head during the argument. He began writing the song and went to sleep. When he awoke, he forgot he had written it and found it later in the morning. He went to the piano and wrote the rest of the song.
- John Lennon - lead vocals, guitar (1965 Epiphone 230TD Casino);
- Paul McCartney - bass (1964 Rickenbacker 4001S);
- George Harrison - sitar;
- Ringo Starr - drums
- "Jai guru deva om", the mantra repeated in the song, means something to the equivalent of: "I give thanks to the great teacher, om". Jai meaning thanks, guru meaning teacher, and deva meaning great. Om is believed to be the sound of the harmony of the universe.
- This song was transmitted into space on February 4, 2008 towards the direction of Polaris. This was meant to celebrate multiple anniversaries including the songs' 40th.
- For the female chorus, two female Apple Scruffs were invited in to sing.
- This was the first and only Beatles song to feature a female chorus.