There's a wonderful interview with Bob Dylan in the LA Times. He talks about songwriting and how he does it.

"You can go anywhere in daily life and have your ears open and hear something, either something someone says to you or something you hear across the room. If it has resonance, you can use it in a song."

"Robert Johnson would sing some song and out of nowhere there would be some kind of Confucius saying that would make you go, 'Wow, where did that come from?' It's important to always turn things around in some fashion."