Callas in Macbeth

Her second selection is her opening scene in Macbeth. It begins superbly, but when the line rises to a high C that had rung out steely-sure at La Scala, her voice cracks, and for an instant she breaks character with an oddly coquettish, apologetic smile. Blink and you would miss it, but if you don’t blink it takes several moments before Lady Macbeth is back in focus.
Will Crutchfield, “The Story of a Voice”