The prince thinks that this guy is the least weird of all the weirdoes he’s met thus far. It may be odd that he lights a lamp on a tiny planet, but his work is beautiful, and is therefore meaningful.
It turns out that the lamplighter has a tough life. His job is put out the lamp in the morning and light it again at night. But his planet is so small and turns so fast that night and day happen each minute. So his work’s never done.
The prince leaves this planet with great respect for this man. The lamplighter is the only one of the men the prince has met who thinks of something else besides himself.