Finally Balthasar von Ulm leapt up from his stool, indicated with a flourish the glass globe, and proclaimed: “My Lords, My Ladies: the void.”

Heinrich said: “My father fell to his knees before the glass globe. Remarkable, he murmured. Miraculous. And here on Earth, right here on Earth! Children, come look, come see, Heinrich, Wilhelmina, Katharina, come look, the void, come see. Margaretha, come see. The scoffing sound my sister produced in response must have come from very deep in her throat, very deep indeed, Father! To express skepticism of that magnitude one must will the walls of one’s throat to bleed. And she said: There is no void, there is no vacuum, that sphere is filled with our atmosphere just as it was before. Tell me, Father, she said slowly, in a singsong, as one would address not a god,” said the Prince, “but a child, or a simpleton, what sensible distinction do you note? How exactly does the nothingness in that sphere make itself known, she asked, to your organs of sense?”

Their father, who now cocked his head and stared more quizzically into the glass globe, said nothing.

Herr von Ulm did not, however, as Margaretha (the astronomer surmised) must have expected that he would, and as he had done a decade ago, slink toward the door.

No, Princess Margaretha’s doubt had evidently been anticipated—and not merely anticipated, but actually incorporated into the performance, for von Ulm began now to pace dramatically back and forth, mumbling to himself The senses!, the senses!, his hands gripped behind his back, a frown on his face as ludicrously pronounced as that on the mask of a tragic figure in an Italian commedia. At last, he came to a halt. He snapped his fingers. “A bird!” he cried. And he brought one hand to his lips and behind it in a stage whisper he hissed at his son, who was also his assistant: “Hans, bring me a bird!” And turning to the audience he clasped his hands before him and said: “Lady Margaretha is quite right. Why should you take my word for it? That would not be in the spirit of our times. Why should you take this globe to be empty simply because I say it is, when perhaps it is filled with air? Perhaps the globe leaks where it meets the tube, or perhaps the pump is a sham, and I a charlatan! Ah, excellent, here is Hans with a bird.” Enter Hans with a pretty little bird on his finger, singing (the bird) a pretty little song, said the Prince, and from where he lay on the floor he sang me “snippets” of the song the bird had sung, the astronomer told Leibniz. “I am mad enough to sing you a snippet of that song, Father, perhaps even several snippets, but I’m not so mad as to sing you the whole birdsong, Father!” said the Prince, laughing. “Snippets only, snippets only! In a world such as mine—for this is my world, not yours, although of course that sentence makes no sense at all aloud, when I say it it sounds stupid—one must come up with one’s own measures of true madness (not the entire birdsong, Heinrich, sing him only snippets thereof! I actually told myself that) and measure oneself, which is to say myself, by them. All nonsense of course. Today, Heinrich, you shall dress him, which is to say yourself, up as a confessor and regale him, which is to say yourself, with your tale, which is to say your murder tale, and when you reach the birdsong part you shall sing him (yourself!) only snippets not the entire thing, that is a sign of your sanity, yes, not singing yourself the entire birdsong is today’s sign of your sanity!”