Every one of Joel's important songs—including the happy ones—are ultimately about loneliness. And it's not 'clever lonely' (like Morrissey) or 'interesting lonely' (like Radiohead); it's 'lonely lonely,' like the way it feels when you're being hugged by someone and it somehow makes you sadder.
Sex, Drugs, and Cocoa Puffs: A Low Culture Manifesto (ed. Simon and Schuster, 2004) - ISBN: 9780743236010