“Father,” said Flambeau at last, “it is my duty, not my curiosity only—­it is my duty to find out, if I can, who committed the crime.”

“Which crime?” asked Father Brown.

“The one we are dealing with, of course,” replied his impatient friend.

“We are dealing with two crimes,” said Brown, “crimes of very different weight—­and by very different criminals.”

Miss Joan Stacey, having collected and put away her papers, proceeded to lock up her drawer.  Father Brown went on, noticing her as little as she noticed him.

“The two crimes,” he observed, “were committed against the same weakness of the same person, in a struggle for her money.  The author of the larger crime found himself thwarted by the smaller crime; the author of the smaller crime got the money.”

“Oh, don’t go on like a lecturer,” groaned Flambeau; “put it in a few words.”

“I can put it in one word,” answered his friend.

Miss Joan Stacey skewered her business-like black hat on to her head with a business-like black frown before a little mirror, and, as the conversation proceeded, took her handbag and umbrella in an unhurried style, and left the room.

“The truth is one word, and a short one,” said Father Brown.  “Pauline Stacey was blind.”

“Blind!” repeated Flambeau, and rose slowly to his whole huge stature.

“She was subject to it by blood,” Brown proceeded.  “Her sister would have started eyeglasses if Pauline would have let her; but it was her special philosophy or fad that one must not encourage such diseases by yielding to them.  She would not admit the cloud; or she tried to dispel it by will.  So her eyes got worse and worse with straining; but the worst strain was to come.  It came with this precious prophet, or whatever he calls himself, who taught her to stare at the hot sun with the naked eye.  It was called accepting Apollo.  Oh, if these new pagans would only be old pagans, they would be a little wiser!  The old pagans knew that mere naked Nature-worship must have a cruel side.  They knew that the eye of Apollo can blast and blind.”

There was a pause, and the priest went on in a gentle and even broken voice.  “Whether or no that devil deliberately made her blind, there is no doubt that he deliberately killed her through her blindness.  The very simplicity of the crime is sickening.  You know he and she went up and down in those lifts without official help; you know also how smoothly and silently the lifts slide.  Kalon brought the lift to the girl’s landing, and saw her, through the open door, writing in her slow, sightless way the will she had promised him.  He called out to her cheerily that he had the lift ready for her, and she was to come out when she was ready.  Then he pressed a button and shot soundlessly up to his own floor, walked through his own office, out on to his own balcony, and was safely praying before the crowded street when the poor girl, having finished her work, ran gaily out to where lover and lift were to receive her, and stepped—­”