"Not words, old man," said Mr. Dark. "Not words in books or words you say but real thoughts, real actions, quick thought, quick action, win the day."
Mr. Dark says this just before he crushes Mr. Halloway's hand. He has taken the boys and is on his way back to the carnival. All appears lost at this point, but shortly afterwards, Mr. Halloway injures and drives off the witch by laughing at her and then goes to the carnival. At the carnival, he acts spontaneously, which is too quick for Mr. Dark to come up with any sort of plan to stop him. Charles Halloway beats Mr. Dark at his own game by using improvised thoughts and actions to guide him in his fight against the carnival. His success validates Mr. Dark's statement, but it also shows that someone of strong mind and good intentions can win the day through spontaneous action, while someone with evil intentions must plan things through.