he little priest only walked
slower and slower in the dim cloister of pine, and at last stopped dead,
on the steps of the house. It was his silent way of acknowledging an
equally silent approach; for there came towards him a presence that
might have satisfied even Calhoun Kidd's demands for a lovely and
aristocratic ghost. It was a young woman in silvery satins of a
Renascence design; she had golden hair in two long shining ropes, and
a face so startingly pale between them that she might have been
chryselephantine--made, that is, like some old Greek statues, out of
ivory and gold. But her eyes were very bright, and her voice, though
low, was confident.

"Father Brown?" she said.

"Mrs Boulnois?" he replied gravely. Then he looked at her and
immediately said: "I see you know about Sir Claude."

"How do you know I know?" she asked steadily.

He did not answer the question, but asked another: "Have you seen your
husband?"

"My husband is at home," she said. "He has nothing to do with this."

Again he did not answer; and the woman drew nearer to him, with a
curiously intense expression on her face.

"Shall I tell you something more?" she said, with a rather fearful
smile. "I don't think he did it, and you don't either." Father Brown
returned her gaze with a long, grave stare, and then nodded, yet more
gravely.

"Father Brown," said the lady, "I am going to tell you all I know, but
I want you to do me a favour first. Will you tell me why you haven't
jumped to the conclusion of poor John's guilt, as all the rest have
done? Don't mind what you say: I--I know about the gossip and the
appearances that are against me."

Father Brown looked honestly embarrassed, and passed his hand across
his forehead. "Two very little things," he said. "At least, one's very
trivial and the other very vague. But such as they are, they don't fit
in with Mr Boulnois being the murderer."

He turned his blank, round face up to the stars and continued
absentmindedly: "To take the vague idea first. I attach a good deal of
importance to vague ideas. All those things that 'aren't evidence'
are what convince me. I think a moral impossibility the biggest of all
impossibilities. I know your husband only slightly, but I think this
crime of his, as generally conceived, something very like a moral
impossibility. Please do not think I mean that Boulnois could not be so
wicked. Anybody can be wicked--as wicked as he chooses. We can direct
our moral