The power of collaboration. Along with “A Day in the Life” this song is held up as the peak of Lennon/McCartney songwriting collaboration. Paul provides the poppy optimism, John the darker realism. The irony is that the two of them could not see eye to eye after 1969 and a once great friendship was lost. It’s a sobering reminder of the importance of compromise and that life is indeed too short for fussing and fighting.