Conductors. I once worked with a well-known mezzo-soprano who was singing Eboli in Don Carlo for the first time. During rehearsals she said she found the slow section of the ‘O Don Fatale’ quite slow. At the premiere, the con-ductor slowed it down and wound down the tempo so much that King Kong with three lungs could not have mastered it. She then paid dearly during the soaring climax at the end.