Having the right body for a role is vitally important, as is knowing how to move it. This is called: ‘le physique du rôle’. I'm almost tempted to regard this as the most important aspect, even more important than the voice. Because the body was the first and earliest instrument of expression. When casting a role, both aspects should be treated at least equally, also with regard to the other roles involved. It's not just the voices that have to fit together, it's their bodies too. Only under this condition can opera attain fulfilment. When this is not the case, hopes of success are stymied from the outset. However beautiful the singing, and however honest the efforts of everyone involved – not least the costume designer – one will always come up against the original defect. And one will always end up dissatisfied. Many opera houses pay far too little attention to this aspect when casting roles. It's not just a big mistake: it's one of the main reasons for the widespread dissatisfaction with opera.

Different languages also produce different attitudes and patterns of movement. One can observe it when children play. Without the slightest knowledge of languages, they use gibberish and mimicry to ape a gangling, gum-chewing American, a wildly gesticulating Italian, a rigid German or a blasé Frenchman. And in opera, too, the cast should be chosen in such a way that the language employed emerges idiomatically and credibly from the physical behaviour and social status of the character.

At this point it can be profitable to consider the world of cartoons. Mickey Mouse and Co. often apply the principles of opera far more consistently than opera does itself. Cartoons offer a perfect transformation of music into physical expression. Of course, cartoon characters can be drawn by hand or in the computer according to the needs of the music. Or, conversely, one can compose the music according to the cartoon characters. This is easier than embarking upon a tiresome search for a real living person able to create movement and music in a single action. And yet opera can learn a lot from cartoons. If roles have been cast with the right vocal and physical characters, the mechanical effect of cartoons can even be recreated on stage. The following episode can prove it.