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.]