The Witch of Prague by F. Marion Crawford

During the short silence which followed, and while the two were still standing opposite to each other, the unhappy man's look did not change. Unorna saw that he was sure of what he said, and a thrill of triumph, as jubilant as his despair was profound ran through her. If she had cared to reason with herself and to examine into her own sincerity, she would have seen that nothing but genuine passion, good or bad, could have lent the assurance of her rival's death such power to flood the dark street with sunshine. But she was already long past doubt upon that question. The enchanter had bound her heart with his spells at the first glance, and the wild nature was already on fire. For one instant the light shot from her eyes, and then sank again as quickly as it had come. She had other impulses than those of love, and subtle gifts of perception that condemned her to know the truth, even when the delusion was most glorious. He was himself deceived, and she knew it.

Beatrice might, indeed, have died long ago. She could not tell. But as she sought in the recesses of his mind, she saw that he had no certainty of it, she saw the black presentiment between him and the image, for she could see the image too. She saw the rival she already hated, not receiving a vision of the reality, but perceiving it through his mind, as it had always appeared to him. For one moment she hesitated still, and she knew that her whole life was being weighed in the trembling balance of that hesitation. For one moment her face became an impenetrable mask, her eyes grew dull as uncut jewels, her breathing ceased, her lips were set like cold marble. Then the stony mask took life again, the sight grew keen, and a gentle sigh stirred the chilly air.