Theme: Something that is used for good can most likely be used for something bad as well.
"I saw him in the air, a man with wings."
"Has anybody else seen this flying man?"
"Here is the man who has made a certain flying machine."
"Hold your tongue. It was all a dream."
The theme is developed through these events because the servant telling the emperor is the beginning of the development. Then the emperor asks if anybody else has seen this man because he is worried about somebody making something like the machine and using it against him. The emperor executing the flier is his way of eliminating a possible threat and the last event fully develops the theme by the emperor telling the servant to keep his mouth shut and not to let anybody use this technology against him.