Walter Rimler, in "The Gershwin Companion" says that this song was introduced by Ella Logan (unseen, on the radio) in the film "The Goldwyn Follies" (1938). Ira wrote some lyrics for the song which were never actually used. It was also during the meetings for this film that Goldwyn made the unfortunate (and highly insulting, to my mind) comment to Gershwin, "Why don't you write hits like Irving Berlin?"