It is an example of Speculum literature.

It is an encyclopedic miscellany of wonders in the manner of speculum literature, divided into three parts (decisiones) concerning history, geography, and physics.

The medieval genre of speculum literature, popular from the twelfth through the sixteenth centuries, was inspired by the urge to encompass encyclopedic knowledge within a single work.

Among his treasures was a mirror through which every province could be seen, the fabled original from which the "speculum literature" of the late Middle Ages and Renaissance was derived, in which the prince's realms were surveyed and his duties laid out.