"I started thinking of the Irish wakes and this idea of, sort of, celebrating a person's life, so I just wrote on the day that I die I'd like jokes to be told and stories of old to be rolled out like carpets …" he said. "I kind of surprised myself, I think, with that. I was glad it came out celebratory instead of kind of morbid."
The songs lyrics describe death as "the start of a journey, to a much better place," and McCartney thinks "that may well be true … Nobody knows for sure, even the Bishop of London."
"I think 'There is more in heaven and Earth than are dreamt of in your philosophy' -- Horatio -- but you know, I think it's a great world," he said. "I think we screw it up probably. I think it basically is a sort of fantastic place, so there's no reason for me to think that after it isn't fantastic, too. But it's a guess."
McCartney's take on life and death might be coming from a deep and personal place. His mother passed away when he was 14 years old, and he lost his first wife Linda to breast cancer in 1998.
"I don't think you ever really get comfortable losing people, you know, losing loved ones. … I'm not the only person on the planet who's experienced that kind of thing," he said. "Everyone loses their parents, pretty much."
The pain of losing his mother at a young age was something he shared with Lennon, whose mother died when he was 16 years old.
"I think music might have been a great healer, I think it was for John and I and when we found each other," he said. "The idea of both of us having this in common. And both combating it together … we certainly bonded and did a lot with it."
McCartney has collaborated with other great artists like Stevie Wonder and Elvis Costello, but said that nothing measured up to working with Lennon.
"John was John. We grew up together, number one. We knew the same records, we wore the same clothes, we liked the same things, we were from the same place," he said. "When we came to write, we came sort of from the same place. We developed together and we did a lot of, I think, very good stuff. So that when you came to write with someone great like Elvis or Stevie, who are great musical talents, it wasn't informed by the same stuff. And John's a hard act to follow and they would be the first to agree with me."
McCartney doesn't find that the Beatles' legacy is a heavy burden to bear, saying that he's still "amazed" that he was part of it all.
"It's a great thing, 'cause I was in 'em. And there were only four people in 'em, so I feel very privileged and very lucky to have been part of that experience," he said. "I can hardly believe it."
Over the years, McCartney has become accustomed to all the attention he gets from the media and from fans, saying, "I made a decision when I was quite a bit younger … I had a decision to either quit knowing that the fame would bring the trappings of fame -- cause we weren't stupid. That's one thing about the Beatles, we weren't just dumb kids; we were quite bright -- or you better realize you're gong to have to live with it."
McCartney's attitude towards the perils of great fame was illustrated in a recent New Yorker profile of the musician. While McCartney was walking in London with the writer, a stranger approached them. The writer was scared, telling McCartney that the man could have been Mark David Chapman. McCartney replied that it could have been Jesus.