rue. A person
can't be quite alone in a street a second before she receives a letter.
She can't be quite alone in a street when she starts reading a letter
just received. There must be somebody pretty near her; he must be
mentally invisible."

"Why must there be somebody near her?" asked Angus.

"Because," said Father Brown, "barring carrier-pigeons, somebody must
have brought her the letter."

"Do you really mean to say," asked Flambeau, with energy, "that Welkin
carried his rival's letters to his lady?"

"Yes," said the priest. "Welkin carried his rival's letters to his lady.
You see, he had to."

"Oh, I can't stand much more of this," exploded Flambeau. "Who is this
fellow? What does he look like? What is the usual get-up of a mentally
invisible man?"

"He is dressed rather handsomely in red, blue and gold," replied the
priest promptly with precision, "and in this striking, and even showy,
costume he entered Himylaya Mansions under eight human eyes; he killed
Smythe in cold blood, and came down into the street again carrying the
dead body in his arms--"

"Reverend sir," cried Angus, standing still, "are you raving mad, or am
I?"

"You are not mad," said Brown, "only a little unobservant. You have not
noticed such a man as this, for example."

He took three quick strides forward, and put his hand on the shoulder of
an ordinary passing postman who had bustled by them unnoticed under the
shade of the trees.

"Nobody ever notices postmen somehow," he said thoughtfully; "yet they
have passions like other men, and even carry large bags where a small
corpse can be stowed quite easily."

The postman, instead of turning naturally, had ducked and tumbled
against the garden fence. He was a lean fair-bearded man of very
ordinary appearance, but as he turned an alarmed face over his shoulder,
all three men were fixed with an almost fiendish squint.

* * * * *

Flambeau went back to his sabres, purple rugs and Persian cat, having
many things to attend to. John Turnbull Angus went back to the lady at
the shop, with whom that imprudent young man contrives to be extremely
comfortable. But Father Brown walked those snow-covered hills under the
stars for many hours with a murderer, and what they said to each other
will never be known.

The Honour of Israel Gow

A stormy evening of olive and silver was closing in, as Father Brown,
wrapped in a grey Scotch plaid, came to the end of a grey Scotch