Cuckoo was listening now with a white face--even her lips looked almost grey. The sunshine still lay over the winter world. The horses trotted. The sables were warm about her. They had nearly left the city behind them and were gaining the heights, on which the air was keener and more life-giving, and from which the outlook was larger and more inspiring. But the girl's gaiety and almost wild sense of vivacity and protectedness had vanished. For the doctor's face and voice had become grave, and his words were weighty with a conviction, which, added to her own knowledge of Julian and Valentine, made her fears unutterable. As the doctor paused she opened her lips as if to speak, but she said nothing. He could not but perceive the cloud that had settled on her, and his manner quickly changed. A brightness, a hopefulness, illumined his face, and he said quickly: "This tragedy is what you and I, but you especially, must prevent." Then Cuckoo spoke at last: "How ever?" she said. "Remember this," he answered. "If Cresswell is mad we must pity him, not condemn him. But we must, above all, fight him. Could I prove his madness the danger would be averted? Possibly time will give me the means of proving it. I have watched him. I shall continue to watch him. But as yet, although I see enough to convince me of his insanity, I don't see enough to convince the world, or, above all, to convince Julian. Therefore never give Julian the slightest hint of what I have told you of to-day. His adoration of Valentine is such that even a hint might easily lead him to regard both you and me as his enemies. Keep your own counsel and mine, but act with me on the silent assumption that Cresswell being a madman, we are justified in fighting him to the bitter end, you and I, with all our forces." "I see," Cuckoo said, a burning excitement beginning to wake in her. "Justified in fighting him, but not in hating him." "Oh," she said, with a much more doubtful accent. "Scarcely any human being, if indeed any, is completely hateful. How then can a human being, whose mind is ill and out of control, be hateful?" said the doctor, gently. She felt herself rebuked, and a quick thought of herself, of what she was, rebuked her too. "I'll try not," she murmured, but with no inward conviction of success.