How does the metaphor of the rattrap serve to highlight the human predicament?

The writer Selma Lagerlof sends a universal theme through all her stories. One cannot imagine how dull and sad a vagabond might be walking slowly along the roads for his bread. The metaphor of the rattrap struck on one such occasion. He was ploding along the road, duly lost in his own meditations.

The whole world about him—the whole world with its lands, seas, cities and villages was nothing but a big rattrap. The world had never existed for any other purpose than to set baits for people to trap them. The world offered riches and joys, heat and clothing, shelter and food exactly as the rattrap offered cheese and pork as bait. As soon as anyone is tempted and he touches the bait, it closes on him and then everything came to an end for him in life.

Like the poor wretch rattrap seller, people get tempted to the pouch baits hung on the window frame, break the window pane and steal the Kroner. For self-temptation people like the peddler don't want to undeceive others about themselves. The touching of the bait always makes people realise that they are caught in the world rattrap now. It is their turn now, they must stop cherish it as their pastime of thinking about the known who get trapped and others who are circling around the trap. They must rise above the baits and shun evil doings like Captain von Stahle.