- In "The Miracle of Moon Crescent" a man miraculously disappears right from his apartment. However, detective inspector Collins seems to imply that the three men waiting outside just weren't practical men and didn't adhere to the facts, unlike himself. This leads to a magnificent retort by one of the witnesses, which is both Crowning Moment of Funny and Crowning Moment of Awesome:
'So you're a practical man, Mr. Collins,' he said, in a voice at once soft and heavy. 'It must be the second or third time you've mentioned in this little conversation that you are a practical man; so I can't be mistaken about that. And a very interesting little fact it is for anybody engaged in writing your life, letters, and table-talk, with portrait at the age of five, daguerreotype of your grandmother and views of the old home-town; and I'm sure your biographer won't forget to mention it along with the fact that you had a pug nose with a pimple on it, and were nearly too fat to walk. And as you're a practical man, perhaps you would just go on practising till you've brought Warren Wynd to life again, and found out exactly how a practical man gets through a deal door. But I think you've got it wrong. You're not a practical man. You're a practical joke; that's what you are. The Almighty was having a bit of fun with us when he thought of you.' With a characteristic sense of drama he went sailing towards the door before the astonished inspector could reply; and no after-recriminations could rob him of a certain appearance of triumph. 'I think you were perfectly right,' said Fenner. 'If those are practical men, give me priests.'
- And later in the same story, professor Vair puts forward an idea that the witnesses just experienced an optical illusion and didn't notice the man going out of the apartment. To which another witness replied:
According to you, a whole procession of Irishmen carrying blunderbusses may have walked through this room while we were talking, so long as they took care to tread on the blind spots in our minds. Miracles of the monkish sort, like materializing a crocodile or hanging a cloak on a sunbeam, seem quite sane compared to you.
- The doctor's diagnosis in "The Secret Garden":
He is not quite cold, but I am afraid he is dead enough.
- Angus' proposal to Laura in "The Invisible Man".
- Father Brown's Eureka Moment in "The Honour of Israel Gow":
Father Brown's pipe fell out of his mouth and broke into three pieces on the gravel path. He stood rolling his eyes, the exact picture of an idiot. "Lord, what a turnip I am!" he kept saying. "Lord, what a turnip!" Then, in a somewhat groggy kind of way, he began to laugh. "The dentist!" he repeated. "Six hours in the spiritual abyss, and all because I never thought of the dentist! Such a simple, such a beautiful and peaceful thought! Friends, we have passed a night in hell; but now the sun is risen, the birds are singing, and the radiant form of the dentist consoles the world." "I will get some sense out of this," cried Flambeau, striding forward, "if I use the tortures of the Inquisition."
- The solution of that story, though it contains a bit of Black Humor.
- Reaction of the landlady to her lodger's murder:
The doctor and the priest made scant reply to her shrill reiterations of her daughter's story, with more disturbing details of her own, to the divided vows of vengeance against Mr Glass for murdering, and against Mr Todhunter for being murdered, or against the latter for having dared to want to marry her daughter, and for not having lived to do it.
- Last-Trick Todd's dinners in "The Mistake of the Machine".
- This little exchange dialogue from "The Head of Caesar":
"I had the honour to ask you why you thought the man's nose was false."
"The wax always spots like that just a little in this weather," answered Father Brown with entire simplicity.
- Flambeau says in "The Fairy Tale of Father Brown":
My information is fragmentary, and only comes from my old friend Grimm. He was a very able detective in the German service, and he tried to arrest me; I arrested him instead, and we had many interesting chats.
- Father Brown in "The Mirror of Magistrate":
All the best people seem to get over garden walls nowadays.
- From the same story:
Everything came back to the enigma of those two empty hours between the time when Buller saw Orm going in at the garden gate, and the time when Father Brown found him apparently still lingering in the garden. He had certainly had the time to commit six murders, and might almost have committed them for want of something to do; for he could give no coherent account of what he was doing.
- Peregrine Smart and his obsession with his goldfish in "The Song of the Flying Fish":
In talking to his neighbours in the little group of new houses that had grown up round the old village green, he lost no time in turning the conversation in the direction of his hobby. To Dr. Burdock, a rising biologist with a resolute chin and hair brushed back like a German’s, Mr. Smart made the easy transition. “You are interested in natural history; have you seen my goldfish?” To so orthodox an evolutionist as Dr. Burdock doubtless all nature was one; but at first sight the link was not close, as he was a specialist who had concentrated entirely upon the primitive ancestry of the giraffe. To Father Brown, from a church in the neighbouring provincial town, he traced a rapid train of thought which touched on the topics of “Rome—St. Peter—fisherman—fish—goldfish.” In talking to Mr. Imlack Smith, the bank manager, a slim and sallow gentleman of dressy appearance but quiet demeanour, he violently wrenched the conversation to the subject of the gold standard, from which it was merely a step to goldfish. In talking to that brilliant Oriental traveller and scholar, Count Yvon de Lara (whose title was French and his face rather Russian, not to say Tartar), the versatile conversationalist showed an intense and intelligent interest in the Ganges and the Indian Ocean, leading naturally to the possible presence of goldfish in those waters. From Mr. Harry Hartopp, the very rich but very shy and silent young gentleman who had recently come down from London, he had at last extorted the information that the embarrassed youth in question was not interested in fishing, and had then added: “Talking about fishing, have you seen my goldfish?”
- Chesterton moght make the simplest sentence funny by his peculiar sense of syntax:
She was the child of a [Father Brown's] sister who had married into a race of refined but impoverished squires. As the squire was dead as well as impoverished, Father Brown stood in the relation of a protector as well as a priest, and in some sense a guardian as well as an uncle.
- Inspector Greenwood in "The Quick One" is very impatient when he's not served fast enough and has some insightful ideas on murderers:
There can’t possibly be anything more easy than murder. I could murder you at this minute—more easily than I can get a drink in this damned bar. The only difficulty is committing a murder without committing oneself as a murderer. It’s this shyness about owning up to a murder; it’s this silly modesty of murderers about their own masterpieces, that makes the trouble. They will stick to this extraordinary fixed idea of killing people without being found out; and that’s what restrains them, even in a room full of daggers. Otherwise every cutler’s shop would be piled with corpses.
- And some Black Humour from the same story:
He now proceeded, as his friend had said, to set an example in truly Christian self-control and brotherhood by reaching the wall with the bound of a tiger, tearing down one of the heavy knives hanging there and sending it smack like a stone from a sling, so that it stuck quivering in the wall exactly half an inch above Mr Raggley’s ear.
- "The Vampire of the Village":
“Mrs Maltravers is not only a widow, but she is the widow of Mr Maltravers.” - “It sounds like a shocking revelation, as you state it,” acknowledged the priest seriously.