In a remote mountain village long ago, there lived a wealthy landowner. Though immensely rich, he was so foolish and prone to blunders that the villagers constantly mocked him.
One day, a foolish rich man visited a wealthy neighbor in a nearby village. Seeing a magnificent three-story house—spacious, bright, and towering—he felt envious, thinking, "I'm just as rich as he is. If he has such a building and I don't, what kind of nonsense is that?" Immediately upon returning home, he summoned the builders and asked, "That new house in the neighboring village—do you know who built it?"
The craftsmen replied, "Yes, that building was built by us." The foolish landlord was delighted and said, "Excellent, build me another one just like it. Remember, I want a three-story house, exactly the same."
The craftsmen agreed, but muttered to themselves, wondering what foolish thing he would do this time. Still, they had to follow orders, so each went about their work.
One day, a wealthy man visited his construction site, looking around with confusion, and asked the workers laying the foundation, "What are you doing?" The craftsmen replied, "Building a three-story house, just as you ordered." The rich man shook his head, "No, no. I want only the third floor—the top one. I don't need the first two stories. Tear them down and build the top floor first." The workers burst out laughing, "If you only want the top floor, we can't build that. Build it yourself!"
The workers had all left, leaving the foolish rich man staring blankly at the foundation. He simply couldn't understand that no matter how skilled the craftsmen, building only the top floor without the two below was an impossible task.
Later, the idiom "Castle in the Air" came to refer to theories, plans, or fictional things detached from reality. It can also metaphorically mean lofty and insightful.
Source: *The Hundred Parables Sutra*, "The Three-Story Tower"
Meaning of the Idiom: Later, the Chinese idiom "空中楼阁" came to describe theories, plans, or fictional things detached from reality.