"Yes. They do many things with their heads, however. I once knew an old woman near Goring on the Thames. She was afflicted with the palsy. She held her head perpetually sideways and it trembled, moving from right to left. Her sailor son brought her home a parrot from one of his voyages. It used to reproduce the old woman's palsied movement of the head exactly. Those grey parrots are always on the watch." Guildea said the last sentence slowly and deliberately, glancing sharply over his wine at Father Murchison, and, when he had spoken it, a sudden light of comprehension dawned in the Priest's mind. He opened his lips to make a swift remark. Guildea turned his bright eyes towards Pitting, who at the moment was tenderly bearing a cheese meringue from the lift that connected the dining-room with the lower regions. The Father closed his lips again. But presently, when the butler had placed some apples on the table, had meticulously arranged the decanters, brushed away the crumbs and evaporated, he said, quickly, "I begin to understand. You think Napoleon is aware of the intruder?" "I know it. He has been watching my visitant ever since the night of that visitant's arrival." Another flash of light came to the Priest. "That was why you covered him with green baize one evening?" "Exactly. An act of cowardice. His behaviour was beginning to grate upon my nerves." Guildea pursed up his thin lips and drew his brows down, giving to his face a look of sudden pain. "But now I intend to follow his investigations," he added, straightening his features. "The week I wasted at Westgate was not wasted by him in London, I can assure you. Have an apple." "No, thank you; no, thank you." The Father repeated the words without knowing that he did so. Guildea pushed away his glass. "Let us come upstairs, then." "No, thank you," reiterated the Father. "Eh?" "What am I saying?" exclaimed the Father, getting up. "I was thinking over this extraordinary affair." "Ah, you're beginning to forget the hysteria theory?" They walked out into the passage. "Well, you are so very practical about the whole matter." "Why not? Here's something very strange and abnormal come into my life. What should I do but investigate it closely and calmly?" "What, indeed?" The Father began to feel rather bewildered, under a sort of compulsion which seemed laid upon him to give earnest attention to a matter that ought to strike him--so he felt--as entirely absurd. When they came into the library his eyes immediately turned, with profound curiosity, towards the parrot's cage. A slight smile curled the Professor's lips. He recognised the effect he was producing upon his friend. The Father saw the smile. "Oh, I'm not won over yet," he said in answer to it. "I know. Perhaps you may be before the evening is over. Here comes the coffee. After we have drunk it we'll proceed to our experiment. Leave the coffee, Pitting, and don't disturb us again." "No, sir."