Doctor Copernicus by John Banville

were still advancing steadily, and Andreas was at his back doing he did not wish to imagine what. The Professor swung himself on his stick in a furious circle
around the table, so stooped now that it appeared he might soon, like some fabulous serpent, clamp his teeth upon his own nether regions and begin to devour himself in his rage. Nicolas, gobbling
and clucking excitedly, pursued him at a hesitant hop.
    “Proof?” the old man snapped. “Proof? A ship sails a certain distance and returns, and the captain comes ashore and agitates the air briefly with words; you call this proof ? By what immutable standards is this a refutation of Ptolemy? You are a nominalist, young man, and you do not even know it.”
    “I a nominalist— I ? Do you not merely say the name of Ptolemy and imagine that all contrary arguments are thus refuted? No no, magister ; I believe not in names, but in
things. I believe that the physical world is amenable to physical investigation, and if astronomers will do no more than sit in their cells counting upon their fingers then they are shirking their
responsibility!”
    The Professor halted. He was pale, and his head trembled alarmingly on its frail stalk of neck, yet he sounded more puzzled than enraged when he said:
    “Ptolemy’s theory saves the phenomena, I have said so already; what other responsibility should it have?”
    Tell him. Tell him.
    “Knowledge, magister , must become perception. The only acceptable theory is that one which explains the phenomena, which explains . . . which . . .” He stared at the
Professor, who had begun to shake all over, while out of his pinched nostrils there came little puffs of an extraordinary harsh dry noise: he was laughing! Suddenly he turned, and pointed with his
stick and asked:
    “What do you say, young fellow? Let us hear your views.”
    Andreas leaned at ease by the window with his arms folded and his face lifted up to the light. A handful of rain glistened on the glass, and a breeze in silence shook the blossoms of the cherry
tree. The unutterable beauty of the world pierced Nicolas’s sinking heart. His brother pondered a moment, and then with the faintest of smiles said lightly:
    “I say, magister , that we must hold fast to sanity and Aristotle.”
    It meant nothing, of course, but it sounded well; O yes, it sounded well. Professor Brudzewski nodded his approval.
    “Ah yes,” he murmured. “Just so.” He turned again to Nicolas. “I think you have been too much influenced by our latterday upstarts, who imagine that they can
unravel the intricacies of God’s all-good creation. You spoke of Regiomontanus: I studied under that great man, and I can assure you that he would have scorned these wild notions you have put
forth today. You question Ptolemy? Mark this: to him who thinks that the ancients are not to be entirely trusted, the gates of our science are certainly closed. He will lie before those gates and
spin the dreams of the deranged about the motion of the eighth sphere, and he will get what he deserves for believing that he can lend support to his own hallucinations by slandering the ancients.
Therefore take this young man’s sound advice, and hold fast to sanity.”
    Nicolas in his dismay felt that he must be emitting a noise, a thin piercing shriek like that of chalk on slate. There was a distinct sensation of shock at the base of his spine, as if he had
sat down suddenly without looking on the spot from whence a chair had been briskly removed. The three conspirators, crowding at his shoulder, regarded him with deep sadness. They were at once
solicitous and sinister. The one with the warts kept his face turned away, unable to look full upon such folly. Andreas, laughing silently, said softly in his brother’s ear:
    “ Bruder, du hast in der Scheisse getreppen .”
    And the fat conspirator giggled. Behind the screens in the hall the secret watcher waited. It was of course—of course!—the green girl. The Professor