The Castle in the Air represents what happens when ideas aren’t grounded in rhyme and reason—and what happens when people get too caught up in their ideas to properly evaluate them.
To say something is a “castle in the sky” (or in the air) is an idiom that means an idea is impossible or not well thought out. So, for instance, starting a business without a plan or enough funding could be a castle in the sky—without those things, the business is never going to get off the ground. The novel suggests that King Azaz and the Mathemagician’s idea to imprison the princesses Rhyme and Reason in a literal Castle in the Air was also a “castle in the sky” idea—before banishing the princesses, they didn’t think through the implications of what would happen without Rhyme and Reason to temper the absurdity in the Kingdom of Wisdom. Many characters note that it was this lack of critical thinking and planning that made the Lands Beyond into the nonsensical, ridiculous, and absurd place it is when Milo arrives.
When Milo finally reaches the princesses, they impress upon him that it’s important to not get so invested in an idea that it’s impossible to look at it from all angles, with rhyme and reason. As the Castle in the Air floats away when the demons cut the staircase, the princesses encourage Milo and the Humbug to let it go, since it was nothing more than a “beautiful prison.” With this, they warn both the characters and readers against getting too caught up in ideas without thinking them through. The consequences, as the novel shows, can be severe.
The Castle in the Air Quotes in The Phantom Tollbooth
“‘Words and numbers are of equal value for, in the cloak of knowledge, one is warp and the other woof. It is no more important to count the sands than it is to name the stars. Therefore, let both kingdoms live in peace.’”
“Everyone was pleased with the verdict. Everyone, that is, but the brothers, who were beside themselves with anger.
“‘What good are these girls if they cannot settle an argument in someone’s favor?’ they growled, since both were more interested in their own advantage than in the truth.”
“But it’s all my fault. For you can’t improve sound by having only silence. The problem is to use each at the proper time.”
“but we would have been here much sooner if I hadn’t made so many mistakes. I’m afraid it’s all my fault.”
“You must never feel badly about making mistakes,” explained Reason quietly, “as long as you take the trouble to learn from them. For you often learn more by being wrong for the right reasons than you do by being right for the wrong reasons.”
“And it’s much the same thing with knowledge, for whenever you learn something new, the whole world becomes that much richer.”
“And remember also,” added the Princess of Sweet Rhyme, “that many places you would like to see and many things you want to know are just out of sight or a little beyond your reach. But someday you’ll reach them all, for what you learn today, for no reason at all, will help you discover all the wonderful secrets of tomorrow.”
“I think I understand,” Milo said, still full of questions and thoughts; “but which is the most important—”
“But what about the Castle in the Air?” the bug objected, not very pleased with the arrangement.
“Let it drift away,” said Rhyme.
“And good riddance,” added Reason, for no matter how beautiful it seems, it’s still nothing but a prison.”
“That’s why, said Azaz, “there was one very important thing about your quest that we couldn’t discuss until you returned.”
“I remember,” said Milo eagerly. “Tell me now.”
“It was impossible,” said the king, looking at the Mathemagician.
“Completely impossible,” said the Mathemagician, looking at the king.
“Do you mean—” stammered the bug, who suddenly felt a bit faint.
“Yes, indeed,” they repeated together; “but if we’d told you then, you might not have gone—and, as you’ve discovered, so many things are possible just as long as you don’t know they’re impossible.”
The Castle in the Air Symbol Timeline in The Phantom Tollbooth
