The Christian element of the album was most obvious in the hymn-like "Word on a Wing", though for some commentators religion, like love, was simply another way for the Duke to "test his numbness". Bowie himself has claimed that in this song, at least, "the passion is genuine". When performing it live in 1999, the singer described it as coming from "the darkest days of my life ... I'm sure that it was a call for help". The closing ballad, "Wild Is the Wind", was the album's sole cover, and has been praised as one of the finest vocal performances of Bowie's career. Bowie was inspired to record it after he met singer/pianist/songwriter Nina Simone (whose version is on the eponymous 1966 album).