The Prince sings this question in the ballroom scene of Rodgers and Hammerstein's Cinderella, the only musical the duo wrote directly for television. It first aired live on CBS in March 1957, watched by an estimated 107 million people.
The chaismus captures a thought every lover has eventually tripped over: is affection a response to beauty, or does affection create the beauty it sees? By folding the sentence back on itself, the lyric refuses to answer, which is of course the answer.
Julie Andrews, who originated the role, said the song was the moment she felt the audience lean in. Decades later, the line still appears in lists of romantic chaismus examples.