The borderland of the brain, where all the monsters are made, moved horribly in the Gaelic O’Brien.  He felt the chaotic presence of all the horse-men and fish-women that man’s unnatural fancy has begotten.  A voice older than his first fathers seemed saying in his ear:  “Keep out of the monstrous garden where grows the tree with double fruit.  Avoid the evil garden where died the man with two heads.”  Yet, while these shameful symbolic shapes passed across the ancient mirror of his Irish soul, his Frenchified intellect was quite alert, and was watching the odd priest as closely and incredulously as all the rest.

Father Brown had turned round at last, and stood against the window, with his face in dense shadow; but even in that shadow they could see it was pale as ashes.  Nevertheless, he spoke quite sensibly, as if there were no Gaelic souls on earth.

“Gentlemen,” he said, “you did not find the strange body of Becker in the garden.  You did not find any strange body in the garden.  In face of Dr. Simon’s rationalism, I still affirm that Becker was only partly present.  Look here!” (pointing to the black bulk of the mysterious corpse) “you never saw that man in your lives.  Did you ever see this man?”

He rapidly rolled away the bald, yellow head of the unknown, and put in its place the white-maned head beside it.  And there, complete, unified, unmistakable, lay Julius K. Brayne.

“The murderer,” went on Brown quietly, “hacked off his enemy’s head and flung the sword far over the wall.  But he was too clever to fling the sword only.  He flung the head over the wall also.  Then he had only to clap on another head to the corpse, and (as he insisted on a private inquest) you all imagined a totally new man.”

“Clap on another head!” said O’Brien staring.  “What other head?  Heads don’t grow on garden bushes, do they?”

“No,” said Father Brown huskily, and looking at his boots; “there is only one place where they grow.  They grow in the basket of the guillotine, beside which the chief of police, Aristide Valentin, was standing not an hour before the murder.  Oh, my friends, hear me a minute more before you tear me in pieces.  Valentin is an honest man, if being mad for an arguable cause is honesty.  But did you never see in that cold, grey eye of his that he is mad!  He would do anything, anything, to break what he calls the superstition of the Cross.  He has fought for it and starved for it, and now he has murdered for it.  Brayne’s crazy millions had hitherto been scattered among so many sects that they did little to alter the balance of things.  But Valentin heard a whisper that Brayne, like so many scatter-brained sceptics, was drifting to us; and that was quite a different thing.  Brayne would pour supplies into the impoverished and pugnacious Church of France; he would support six Nationalist newspapers like The Guillotine.  The battle was already balanced on a point, and the