- Sherlock Holmes: [about Inspector Jones] He is an absolute imbecile at his profession but he does have the tenacity of a lobster when he gets his claws into someone.
- Vincent Spaulding: I beg you to take your filthy hands off me! You may not be aware that I have royal blood in my veins. And be so kind as to say "sir" and "please" when you address me.
- Athelney Jones: All right. Would you please, sir, mind marching upstairs where we'll get a cab to transport your highness to the police station?
- Vincent Spaulding: That's better. Gentlemen.
- [bows]
- [first lines]
- Sherlock Holmes: Hm!
- Dr. John Watson: [entering] Oh. Sorry, Holmes.
- Sherlock Holmes: No no. You couldn't have come at a better time.
- Dr. John Watson: Well, I was, I was afraid you were engaged.
- Sherlock Holmes: I am. Very much so.
- Dr. John Watson: What are you going to do?
- Sherlock Holmes: To smoke. It is quite a three-pipe problem, and I beg that you won't speak to me for fifty minutes.
- Athelney Jones: [about Sherlock Holmes] Our friend here's a wonderful man for starting a chase. All he needs is an old dog to help him do the running down.
- Sherlock Holmes: You, sir, should know, being not only the resident manager but also the director.
- Mr. Merryweather: I should know and I do know!
- [last lines]
- Sherlock Holmes: Sometimes I think my whole life is spent in one long effort to escape from the commonplaces of existence.
- Dr. John Watson: No no, you are a benefactor of the race, Holmes.
- Sherlock Holmes: Well, maybe it is of some little use after all. "L'homme c'est rien - l'oeuvre c'est tout," as Gustave Flaubert wrote to Georges Sand. Hm?
- Sherlock Holmes: [talking of John Clay] His grandfather was a royal duke, and he himself was educated at Eaton and Oxford. So Watson, bring the gun.
- Sherlock Holmes: Now I begin to think my reputation, such as it is, will suffer shipwreck if I am so candid. 'Omne ignotum pro magnifico.'
- Dr. John Watson: [to Mr. Wilson] Everything becomes commonplace by explanation.
- Sherlock Holmes: Watson, that is a very loose translation!