“Bel canto does not mean beautiful singing alone. It is, rather, the technique demanded by the composers of this style — Donizetti, Rossini, and Bellini. It is the same attitudes and demands of Mozart and Beethoven, for example, the same approach and the same technical difficulties faced by instrumentalists. You see, a musician is a musician. A singer is no different from an instrumentalist except that we have words. You don't excuse things in a singer you would not dream of excusing in a violinist or pianist. There is no excuse for not having a trill, for not doing the acciaccatura, for not having good scales. Look at your scores! There are technical things written there to be performed, and they must be performed whether you like it or not. How will you get out of a trill? How will you get out of scales when they are written there, staring you in the face? It is not enough to have a beautiful voice. What does that mean? When you interpret a role, you have to have a thousand colors to portray happiness, joy, sorrow, fear. How can you do this with only a beautiful voice? Even if you sing harshly sometimes, as I have frequently done, it is a necessity of expression. You have to do it, even if people will not understand. But in the long run they will, because you must persuade them of what you're doing.”

Callas : The Art and the Life (1974)