 McCartney said he wrote the song in response to accusations, including one from his former bandmate John Lennon, that McCartney only liked writing music about love. Paul said he was worried he was buying into that idea and wondered if he needed to be more grounded and sophisticated. But then McCartney realized, he said, that's exactly what love is. It's worldly. He'd been given a reputation and needed to stand by it, and so he did.