All glanced round and the short priest went across and looked down in silence at the tool where it lay. It was one of the smallest and the lightest of the hammers, and would not have caught the eye among the rest; but on the iron edge of it were blood and yellow hair.
  After a silence the short priest spoke without looking up, and there was a new note in his dull voice. 'Mr Gibbs was hardly right,' he said, 'in saying that there is no mystery. There is at least the mystery of why so big a man should attempt so big a blow with so little a hammer.'
  'Oh, never mind that,' cried Gibbs, in a fever. 'What are we to do with Simeon Barnes?'
  'Leave him alone,' said the priest quietly. 'He is coming here of himself. I know those two men with him. They are very good fellows from Greenford, and they have come over about the Presbyterian chapel.'
  Even as he spoke the tall smith swung round the corner of the church, and strode into his own yard. Then he stood there quite still, and the hammer fell from his hand. The inspector, who had preserved impenetrable propriety, immediately went up to him.
  'I won't ask you, Mr Barnes,' he said, 'whether you know anything about what has happened here. You are not bound to say. I hope you don't know, and that you will be able to prove it. But I must go through the form of arresting you in the King's name for the murder of Colonel Norman Bohun.'
  'You are not bound to say anything,' said the cobbler in officious excitement. 'They've got to prove everything. They haven't proved yet that it is Colonel Bohun, with the head all smashed up like that.'
  'That won't wash,' said the doctor aside to the priest. 'That's out of the detective stories. I was the colonel's medical man, and I knew his body better than he did. He had very fine hands, but quite peculiar ones. The second and third fingers were the same length. Oh, that's the colonel right enough.'
  As he glanced at the brained corpse upon the ground the iron eyes of the motionless blacksmith followed them and rested there also.
  'Is Colonel Bohun dead?' said the smith quite calmly. 'Then he's damned.'
  'Don't say anything! Oh, don't say anything,' cried the atheist cobbler, dancing about in an ecstasy of admiration of the English legal system. For no man is such a legalist as the good Secularist.
  The blacksmith turned on him over his shoulder the august face of a fanatic.
  'It's well for you infidels to dodge like foxes because the world's law favours you,' he said; 'but God guards His own in His pocket, as you shall see this day.'
  Then he pointed to the colonel and said: 'When did this dog die in his sins?'
  'Moderate your language,' said the doctor.
  'Moderate the Bible's language, and I'll moderate mine. When did he die?'
  'I saw him alive at six o'clock this morning,' stammered Wilfred Bohun.
  'God is good,' said the smith. 'Mr Inspector, I have not the slightest objection to being arrested. It is you who may object to arresting me. I don't mind leaving the court without a stain on my character. You do mind perhaps leaving the court with a bad set-back in your career.'
  The solid inspector for the first time looked at the blacksmith with a lively eye; as did everybody else, except the short, strange priest, who was still looking down at the little hammer that had dealt the dreadful blow.
  'There are two men standing outside this shop,' went on the blacksmith with ponderous lucidity, 'good tradesmen in Greenford whom you all know, who will swear that they saw me from before midnight till daybreak and long after in the committee room of our Revival Mission, which sits all night, we save souls so fast. In Greenford itself twenty people could swear to me for all that time. If I were a heathen, Mr Inspector, I would let you walk on to your downfall. But as a Christian man I feel bound to give you your chance, and ask you whether you will hear my alibi now or in court.'
  The inspector seemed for the first time disturbed, and said, 'Of course I should be glad to clear you altogether now.'
  The smith walked out of his yard with the same long and easy stride, and returned to his two friends from Greenford, who were indeed friends of nearly everyone present. Each of them said a few words which no one ever thought of disbelieving. When they had spoken, the innocence of Simeon stood up as solid as the great church above them.
  One of those silences struck the group which are more strange and insufferable than any speech. Madly, in order to make conversation, the curate said to the Catholic priest:
  'You seem very much interested in that hammer, Father Brown.'
  'Yes, I am,' said Father Brown; 'why is it such a small hammer?'
  The doctor swung round on him.
  'By George, that's true,' he cried; 'who would use a little hammer with ten larger hammers lying about?'
  Then he lowered his voice in the curate's ear and said: 'Only the kind of person that can't lift a large hammer. It is not a question of force or courage between the sexes. It's a question of lifting power in the shoulders. A bold woman could commit ten murders with a light hammer and never turn a hair. She could not kill a beetle with a heavy one.'
  Wilfred Bohun was staring at him with a sort of hypnotised horror, while Father Brown listened with his head a little on one side, really interested and attentive. The doctor went on with more hissing emphasis:
  'Why do these idiots always assume that the only person who hates the wife's lover is the wife's husband? Nine times out of ten the person who most hates the wife's lover is the wife. Who knows what insolence or treachery he had shown her â look there!'
  He made a momentary gesture towards the red-haired woman on the bench. She had lifted her head at last and the tears were drying on her splendid face. But the eyes were fixed on the corpse with an electric glare that had in it something of idiocy.
  The Rev. Wilfred Bohun made a limp gesture as if waving away all desire to know; but Father Brown, dusting off his sleeve some ashes blown from the furnace, spoke in his indifferent way.
  'You are like so many doctors,' he said; 'your mental science is really suggestive. It is your physical science that is utterly impossible. I agree that the woman wants to kill the co-respondent much more than the petitioner does. And I agree that a woman will always pick up a small hammer instead of a big one. But the difficulty is one of physical impossibility. No woman ever born could have smashed a man's skull out flat like that.' Then he added reflectively, after a pause: 'These people haven't grasped the whole of it. The man was actually wearing an iron helmet, and the blow scattered it like broken glass. Look at that woman. Look at her arms.'
  Silence held them all up again, and then the doctor said rather sulkily: 'Well, I may be wrong; there are objections to everything. But I stick to the main point. No man but an idiot would pick up that little hammer if he could use a big hammer.'
  With that the lean and quivering hands of Wilfred Bohun went up to his head and seemed to clutch his scanty yellow hair. After an instant they dropped, and he cried: 'That was the word I wanted; you have said the word.'
  Then he continued, mastering his discomposure: 'The words you said were, "No man but an idiot would pick up the small hammer."'
  'Yes,' said the doctor. 'Well?'
  'Well,' said the curate, 'no man but an idiot did.' The rest stared at him with eyes arrested and riveted, and he went on in a febrile and feminine agitation.
  'I am a priest,' he cried unsteadily, 'and a priest should be no shedder of blood. I â I mean that he should bring no one to the gallows. And I thank God that I see the criminal clearly now â because he is a criminal who cannot be brought to the gallows.'
  'You will not denounce him?' inquired the doctor.
  'He would not be hanged if I did denounce him,' answered Wilfred with a wild but curiously happy smile. 'When I went into the church this morning I found a madman praying there â that poor Joe, who has been wrong all his life. God knows what he prayed; but with such strange folk it is not incredible to suppose that their prayers are all upside down. Very likely a lunatic would pray before killing a man. When I last saw poor Joe he was with my brother. My brother was mocking him.'
  'By Jove!' cried the doctor, 'this is talking at last. But how do you explain â '
  The Rev. Wilfred was almost trembling with the excitement of his own glimpse of the truth. 'Don't you see; don't you see,' he cried feverishly; 'that is the only theory that covers both the queer things, that answers both the riddles. The two riddles are the little hammer and the big blow. The smith might have struck the big blow, but would not have chosen the little hammer. His wife would have chosen the little hammer, but she could not have struck the big blow. But the madman might have done both. As for the little hammer â why, he was mad and might have picked up anything. And for the big blow, have you never heard, doctor, that a maniac in his paroxysm may have the strength of ten men?'
  The doctor drew a deep breath and then said, 'By golly, I believe you've got it.'
  Father Brown had fixed his eyes on the speaker so long and steadily as to prove that his large grey, ox-like eyes were not quite so insignificant as the rest of his face. When silence had fallen he said with marked respect: 'Mr Bohun, yours is the only theory yet propounded which holds water every way and is essentially unassailable. I think, therefore, that you deserve to be told, on my positive knowledge, that it is not the true one.' And with that the odd little man walked away and stared again at the hammer.
  'That fellow seems to know more than he ought to,' whispered the doctor peevishly to Wilfred. 'Those popish priests are deucedly sly.'
  'No, no,' said Bohun, with a sort of wild fatigue. 'It was the lunatic. It was the lunatic.'
  The group of the two clerics and the doctor had fallen away from the more official group containing the inspector and the man he had arrested. Now, however, that their own party had broken up, they heard voices from the others. The priest looked up quietly and then looked down again as he heard the blacksmith say in a loud voice:
  'I hope I've convinced you, Mr Inspector. I'm a strong man, as you say, but I couldn't have flung my hammer bang here from Greenford. My hammer hasn't got wings that it should come flying half a mile over hedges and fields.'
  The inspector laughed amicably and said: 'No, I think you can be considered out of it, though it's one of the rummiest coincidences I ever saw. I can only ask you to give us all the assistance you can in finding a man as big and strong as yourself. By George! you might be useful, if only to hold him! I suppose you yourself have no guess at the man?'
  'I may have a guess,' said the pale smith, 'but it is not at a man.' Then, seeing the scared eyes turn towards his wife on the bench, he put his huge hand on her shoulder and said: 'Nor a woman either.'
  'What do you mean?' asked the inspector jocularly. 'You don't think cows use hammers, do you?'
  'I think no thing of flesh held that hammer,' said the blacksmith in a stifled voice; 'mortally speaking, I think the man died alone.'
  Wilfred made a sudden forward movement and peered at him with burning eyes.
  'Do you mean to say, Barnes,' came the sharp voice of the cobbler, 'that the hammer jumped up of itself and knocked the man down?'
  'Oh, you gentlemen may stare and snigger,' cried Simeon; 'you clergymen who tell us on Sunday in what a stillness the Lord smote Sennacherib. I believe that One who walks invisible in every house defended the honour of mine, and laid the defiler dead before the door of it. I believe the force in that blow was just the force there is in earthquakes, and no force less.'
  Wilfred said, with a voice utterly undescribable: 'I told Norman myself to beware of the thunderbolt.'
  'That agent is outside my jurisdiction,' said the inspector with a slight smile.
  'You are not outside His,' answered the smith; 'see you to it,' and, turning his broad back, he went into the house.
  The shaken Wilfred was led away by Father Brown, who had an easy and friendly way with him. 'Let us get out of this horrid place, Mr Bohun,' he said. 'May I look inside your church? I hear it's one of the oldest in England. We take some interest, you know,' he added with a comical grimace, 'in old English churches.'
  Wilfred Bohun did not smile, for humour was never his strong point. But he nodded rather eagerly, being only too ready to explain the Gothic splendours to someone more likely to be sympathetic than the Presbyterian blacksmith or the atheist cobbler.
  'By all means,' he said; 'let us go in at this side.' And he led the way into the high side entrance at the top of the flight of steps. Father Brown was mounting the first step to follow him when he felt a hand on his shoulder, and turned to behold the dark, thin figure of the doctor, his face darker yet with suspicion.
  'Sir,' said the physician harshly, 'you appear to know some secrets in this black business. May I ask if you are going to keep them to yourself?'
  'Why, doctor,' answered the priest, smiling quite pleasantly, 'there is one very good reason why a man of my trade should keep things to himself when he is not sure of them, and that is that it is so constantly his duty to keep them to himself when he is sure of them. But if you think I have been discourteously reticent with you or anyone, I will go to the extreme limit of my custom. I will give you two very large hints.'
  'Well, sir?' said the doctor gloomily.
  'First,' said Father Brown quietly, 'the thing is quite in your own province. It is a matter of physical science. The blacksmith is mistaken, not perhaps in saying that the blow was divine, but certainly in saying that it came by a miracle. It was no miracle, doctor, except in so far as man is himself a miracle, with his strange and wicked and yet half-heroic heart. The force that smashed that skull was a force well known to scientists â one of the most frequently debated of the laws of nature.'