Listen to the sound clip But I do know one thing. from The Wiz: But I do know one thing. But I do know one thing. This sound is from The Wiz The Wiz is a beloved musical film that was released in 1978. It is an adaptation of the Broadway musical of the same name, which itself was a modern retelling of L. Frank Baum's classic novel "The Wonderful Wizard of Oz." Dir… Go to the full soundboardwith more sound clips Search