4 ideas
Each secular story is told plainly first, then decoded point by point in a 'Moralitas' section. There the emperor becomes God, the knight the soul, and the wicked steward the devil. Separating narrative pleasure from doctrinal payload lets the preacher hold attention with entertainment and then reassign every element to a fixed theological meaning.
The compilers attach Christian meanings to pagan, Eastern and folk tales whose plots have no religious content, and the fit between tale and moral is often strained or arbitrary. The meaning is imposed by the interpreter's key rather than found in the story itself. That makes the narrative a reusable vessel that can be redirected toward whatever lesson the teacher needs.
A maiden must choose among caskets of gold, silver and lead, each bearing an inscription. The choice exposes the chooser's values: judging by outward splendour leads to death, and accepting apparent lowliness leads to reward.
The collection assumes that audiences who ignore abstract exhortation will listen to vivid tales of emperors, adulteresses, tricksters and marvels. A memorable story makes the attached moral easier to recall. The anthology is therefore a stockpile of retrievable exempla, organised so that a speaker can pull out a ready-made hook for a given sermon theme.