Poetry provides other ways to talk about meaning and communication in music. Even toddlers use their voices to convey feelings about the words they are speaking. What happens when there is a disconnect between the literal meaning of the words and the affect of the speaker?
For example, imagine a tone of voice for the words “Today is the picnic I have been looking forward to all week.” Probably it would be excited and happy. But, if you look out the window, see a storm rolling in and then say, “Oh no, was that thunder? I guess we can’t go after all.”… you would have to change the emotional message.
How does this translate to music?
Should the development of the Allegro aperto of Mozart’s 5th violin concerto be played the same way as the opening? The movement begins rather jauntily in A major. At bar 118, suddenly you find yourself in c# minor! This is pretty high drama, and to my mind that calls for very different emotional content.