In 1966, after drawing “only” 50,000 fans for a show at Shea Stadium, the Beatles were fed up with touring. In an interview years later with Paul, George and Ringo seated around a table, McCartney said, “We were getting worse and worse as a band while all those people were screaming. It was lovely that they liked us but we couldn’t hear to play.” They could no longer hear the music. When that happened, they lost their meaning. They had to go back to the studio to find their sound again. 

When the...