When my son was about 2 he used to have periods of complete craziness where he'd run around causing chaos and smashing the house up. One day I had some music on and put let it be on. He stopped instantly, sat down and just listened in sheer awe. I sing it to him most nights to calm him down before bed (he's nearly 5 now). It was a great song before that, but it's taken on a higher power now.