The song "Sitting in the Rain" by John Mayall & The Bluesbreakers is a blues ballad about heartbreak and longing. The protagonist of the song is sitting outside in the rain, under an old green tree, desperately waiting for his lover to come back to him. He is suffering both physically and emotionally, with a blister on his heel and a splinter in his heart. The lyrics express his sadness and regret for the relationship that has ended, and his confusion about why they had to part ways. Despite his apologies, he acknowledges that they are not allowed to be together, adding to his sense of despair and hopelessness. The song is a classic example of the blues genre, with its mournful lyrics and soulful instrumentation.