Stray Thoughts

If I could ask Paul McCartney one question, it'd be this:

In the song "Paperback Writer" the lyric goes:

Dear Sir or Madam, will you read my book?
It took me years to write, will you take a look?
It's based on a novel by a man named Lear

"Based on a novel by a man named Lear?" When you wrote this song, did you have any idea what the hell a paperback was?