Riccardo Muti explains Verdi to Opera News:
Verdi, as I said before, tells you exactly what is the mood, what is the atmosphere. Sometimes he indicates even the way a singer must come onstage. For example, in La Traviata. [He hums a bit.] That is the entrance of Papa Germont. Verdi writes music that tells you even how fast Germont must come in or how slow he must come in. The interval [hums again] is so large, it defines very well how pompous and irritating and not nice is this person who is coming in to speak to Violetta.
I'm using this example because I saw a Traviata of a very famous stage director — I will not mention the name — in which during [hums entrance music] the singer for Germont was not onstage. Then after this phrase ended — in the silence — Germont came in very fast and very angry. [Growls.] "Madamigella Valery?"This is more example of a director who doesn't hear the music and works against the music. Verdi's not telling you from which direction Germont comes, how he is dressed, et cetera, et cetera. But through this music, he is telling you the personality of this man, his low and heavy way of coming into this woman's house. Verdi gives you this man's soul in this music, yes?
Yes.
(OC's favorite bit, 100% Riccardone: ""Sorry. Sorry Verdi, for this E-flat I will make an exception."). He sees dead composers, that's the secret of his success.