When Sister Anne came in a few minutes later, she was astonished at what she saw.  The girl crouched at the window, her hands on the sill, staring out at the sky in an attitude of unmistakable horror.

Sister Anne came across the room quickly, setting down something on the table as she passed.  She touched the girl on the shoulder.

“My dear, what is it?”

There was a long sobbing breath, and Mabel turned, rising as she turned, and clutched the nurse with one shaking hand, pointing out with the other.

“There!” she said.  “There—­look!”

“Well, my dear, what is it?  I see nothing.  It is a little dark!”

“Dark!” said the other.  “You call that dark!  Why, why, it is black—­black!”

The nurse drew her softly backwards to the chair, turning her from the window.  She recognised nervous fear; but no more than that.  But Mabel tore herself free, and wheeled again.

“You call that a little dark,” she said.  “Why, look, sister, look!”

Yet there was nothing remarkable to be seen.  In front rose up the feathery hand of an elm, then the shuttered windows across the court, the roof, and above that the morning sky, a little heavy and dusky as before a storm; but no more than that.

“Well, what is it, my dear?  What do you see?”

“Why, why ... look! look!—­There, listen to that.”

A faint far-away rumble sounded as the rolling of a waggon—­so faint that it might almost be an aural delusion.  But the girl’s hands were at her ears, and her face was one white wide-eyed mask of terror.  The nurse threw her arms round her.

“My dear,” she said, “you are not yourself.  That is nothing but a little heat-thunder.  Sit down quietly.”

She could feel the girl’s body shaking beneath her hands, but there was no resistance as she drew her to the chair.

“The lights! the lights!” sobbed Mabel.

“Will you promise me to sit quietly, then?”

She nodded; and the nurse went across to the door, smiling tenderly; she had seen such things before.  A moment later the room was full of exquisite sunlight, as she switched the handle.  As she turned, she saw that Mabel had wheeled herself round in the chair, and with clasped hands was still staring out at the sky above the roofs; but she was plainly quieter again now.  The nurse came back, and put her hand on her shoulder.

“You are overwrought, my dear....  Now you must believe me.  There is nothing to be frightened of.  It is just nervous excitement....  Shall I pull down the blind?”

Mabel turned her face....  Yes, certainly the light had reassured her.  Her face was still white and bewildered, but the steady look was coming back to her eyes, though, even as she spoke, they wandered back more than once to the window.

“Nurse,” she said more quietly, “please look again and tell me if you see nothing.  If you say there is nothing I will believe that I am going mad.  No; you must not touch the blind.”