From a letter by Stephen Vincent Benét to William Rose Benét (January 15, 1915)

Magic [a play by Chesterton] is fine too. The place where the red light turns blue is a great moment, great, GREAT. There certainly are devils.

-Selected Letters of Steven Vincent Benét, p. 9

[I know nothing about  Benét, but a quick trip to Google informs me that a short story he wrote was the basis for the musical Seven Brides for Seven Brothers.]

Conjurer. [Seriously.] There was little pleasure in her life.

Patricia. There is little, a very little, in everybody's. The question is, what kind? We can't turn life into a pleasure. But we can choose such pleasures as are worthy of us and our immortal souls.

-Magic (1913)

"The Duke is the kindest of men, and always trying to please everybody. He generally finishes by pleasing nobody."

Doctor. [Sitting down and lighting a cigar.] Well, yes. The Duke does suffer a little from absence [puts his cigar in his mouth and pulls during the pause] of mind. He is all for compromise. Don't you know the kind of man who, when you talk to him about the five best breeds of dog, always ends up by buying a mongrel? The Duke is the kindest of men, and always trying to please everybody. He generally finishes by pleasing nobody.

-Magic (1913)

"Nothing's incompatible, you know—except husband and wife and so on."

Duke. [...] Well, Professor, what's the news in the conjuring world?

Conjurer. I fear there is never any news in the conjuring world.

Duke. Don't you have a newspaper or something? Everybody has a newspaper now, you know. The—er—Daily Sword-Swallower or that sort of thing?

Conjurer. No, I have been a journalist myself; but I think journalism and conjuring will always be incompatible.

Duke. Incompatible—Oh, but that's where I differ—that's where I take larger views! Larger laws, as old Buffle said. Nothing's incompatible, you know—except husband and wife and so on; you must talk to Morris about that. It's wonderful the way incompatibility has gone forward in the States.

Conjurer. I only mean that the two trades rest on opposite principles. The whole point of being a conjurer is that you won't explain a thing that has happened.

Duke. Well, and the journalist?

Conjurer. Well, the whole point of being a journalist is that you do explain a thing that hasn't happened.

Duke. But you'll want somewhere to discuss the new tricks.

Conjurer. There are no new tricks. And if there were we shouldn't want 'em discussed.

Duke. I'm afraid you're not really advanced. Are you interested in modern progress?

Conjurer. Yes. We are interested in all tricks done by illusion.

-Magic (1913)

"I object to a quarrel because it always interrupts an argument."

DOCTOR. Then we all agree there shall be no quarrel.

SMITH. May I say a word? I have a great dislike of a quarrel, for a reason quite beyond my duty to my cloth.

MORRIS. And what is that?

SMITH. I object to a quarrel because it always interrupts an argument. May I bring you back for a moment to the argument? You were saying that these modern conjuring tricks are simply the old miracles when they have once been found out. But surely another view is possible. When we speak of things being sham, we generally mean that they are imitations of things that are genuine. Take that Reynolds over there of the Duke's great-grandfather. [Points to a picture on the wall.] If I were to say it was a copy....

MORRIS. Wal, the Duke's real amiable; but I reckon you'd find what you call the interruption of an argument.

SMITH. Well, suppose I did say so, you wouldn't take it as meaning that Sir Joshua Reynolds never lived. Why should sham miracles prove to us that real Saints and Prophets never lived. There may be sham magic and real magic also.

[The Conjurer raises his head and listens with a strange air of intentness.

SMITH. There may be turnip ghosts precisely because there are real ghosts. There may be theatrical fairies precisely because there are real fairies. You do not abolish the Bank of England by pointing to a forged bank-note.

-Magic (1913)

George Bernard Shaw's review of GKC's first play Magic

George Bernard Shaw, himself a famous playwright, of course, in a review (which appeared in the May 13, 1916 edition of the New Statesman) of Julius West's G.K. Chesterton: A Critical Study, in which Shaw describes his thoughts on Chesterton's play Magic (You can read Magic at this link.)

I agree very heartily with Mr. West as to Mr. Chesterton's success in his single essay as a playwright. I shirk the theatre so lazily that I have lost the right to call myself a playgoer; but circumstances led to my seeing Magic performed several times, and I enjoyed it more and more every time. Mr. Chesterton was born with not only brains enough to see something more in the world than sexual intrigue, but with all the essential tricks of the stage at his fingers' ends; and it was delightful to find that the characters which seem so fantastic and even ragdolly (stage characters are usually waxdolly) in his romances became credible and solid behind the footlights, just the opposite of what his critics expected. The test is a searching one; an exposure to it of many moving and popular scenes in novels would reveal the fact that they are physically impossible and morally absurd. Mr Chesterton is in the English tradition of Shakespeare and Fielding and Scott and Dickens, in which you must grip your character so masterfully that you can play with it in the most extravagant fashion...The Duke in Magic is much better than Micawber or Mrs. Wilfer, neither of whom can bear the footlights because, like piping bullfinches, they have only one tune, whilst the Duke sets everything in the universe to his ridiculous music. That is the Shakespearian touch. Is it grateful to ask for more?

MORRIS. Well, well, they didn't know everything in those old times.

SMITH. No, and in those old times they knew they didn't.

-Magic (1913)