"That that is is that that is not is not is that it it is"
This is a grammar technique taught in high school, the point of the exercise is to punctuate the phrase or phrases to make grammatical sense. "That that is, is. That that is not, is not. Is that it? It is." Actors do the same to words written in a script. They take the words and make the words and phrases into something meaningful. A musical takes it one step further by including additional elements of intentional meter and tone. When Alan J. Lerner, along with Frederick Loewe, adapted George Bernard Shaw's 1913 Pygmalion into the 1956 musical My Fair Lady, he added yet another level to the tale, which carried over into the 1964 movie version, directed by George Cukor.
The musical prose gave the audience a different perspective into the lives of the characters. "Just you wait 'Enry 'Iggins," displayed the Eliza Doolittle's anger through Audrey Hepburn on screen much more blatantly than words or the best non-verbal communication that Pygmalion star Wendy Hiller could have displayed. Henry Higgins' excitement toward his profession came to life in his tune/speech, rendered on screen by Rex Harrison, in the study. The music even gave Eliza's father, Alfred P. Doolittle, an extension of the supporting role he played in Pygmalion. The catchy songs like "Get Me to the Church on Time" and "With a Little Bit of Luck," not only made Doolittle, as portrayed by Stanley Holloway, a likeable character, but also gave audiences something to hum all the way home.
Plays, films and musicals have reasons for production beyond education and conveying the author's message. These productions are to entertain audiences and musicals give an extra special break from reality. Pygmalion is humorous, but to some audiences the comedy does not hit straight in the gut, but My Fair Lady nearly behooves audiences to at least smile if not walk away humming.