4 ideas
Postman Kolbaba falls asleep in the post office and sees the little post-office goblins, who judge letters by feel: sincere letters are warm and empty, formal ones are cold. Among them is a letter with no address and no stamp, a marriage proposal. Kolbaba walks for a year and a day to find its intended recipient, and the lovers are united because a postman treated delivery as a moral duty rather than a procedure.
In the postman's tale, a letter's value lies in the feeling behind it, and that feeling is sensible to the touch as warmth or coldness. Heartfelt letters glow warm, while business and perfunctory letters are cold. The idea separates the informational content of communication from its emotional charge and treats the charge as what matters.
The magic then works by that trade's rules: goblins run the post office and doctors treat a magician as a patient. Seeing modern jobs this way reveals that institutions develop their own mythologies, and that ordinary work can hold wonder when viewed from inside it.
Čapek places water sprites, goblins, robbers and princesses in a world of post offices, police stations and medical practices. Rather than disappearing, the fantastic takes on modern institutional forms and speaks in their plain, bureaucratic tone. The comedy comes from treating the supernatural with the matter-of-fact logic of daily routine.