“[Serafin was] an extraordinary coach, sharp as a vecchio lupo [old wolfe]. He opened a world to me, showed me there was a reason for everything, that even fiorature and trills… have a reason in the composer's mind, that they are the expression of the stato d'animo [state of mind] of the character — that is, the way he feels at the moment, the passing emotions that take hold of him. He would coach us for every little detail, every movement, every word, every breath. One of the things he told me — and this is the basis of bel canto — is never to attack a note from underneath or from above, but always to prepare it in the face. He taught me that pauses are often more important than the music. He explained that there was a rhythm — these are the things you get only from that man! — a measure for the human ear, and that if a note was too long, it was no good after a while. A fermata always must be measured, and if there are two fermate close to one another in the score, you ignore one of them. He taught me the proportions of recitative — how it is elastic, the proportions altering so slightly that only you can understand it…. But in performance he left you on your own. "When I am in the pit, I am there to serve you, because I have to save my performance." he would say. We would look down and feel we had a friend there. He was helping you all the way. He would mouth all the words. If you were not well, he would speed up the tempo, and if you were in top form, he would slow it down to let you breathe, to give you room. He was breathing with you, living the music with you, loving it with you. It was elastic, growing, living.”

Callas : The Art and the Life (1974)