Callas articulates all of the trills, and she binds them into the line more expressively than anyone else; they are not an ornament but a form of intensification. Part of the wonder in this performance is the chiaroscuro through her tone—the other side of not singing full-out all the way through. One of the vocal devices that create that chiaroscuro is a varying rate of vibrato; another is her portamento, the way she connects the voice from note to note, phrase to phrase, lifting and gliding. This is never a sloppy swoop, because its intention is as musically precise as it is in great string playing. In this aria, Callas uses more portamento, and in greater variety, than any other singer ... Callas is not creating "effects", as even her greatest rivals do. She sees the aria as a whole, "as if in an aerial view", as Sviatoslav Richter's teacher observed of his most famous pupil; simultaneously, she is on earth, standing in the courtyard of the palace of Aliaferia, floating her voice to the tower where her lover lies imprisoned.