In it, he outlined his ideas for the hierarchical classification of the natural world, dividing it into the animal kingdom (regnum animale), the plant kingdom (regnum vegetabile), and the "mineral kingdom" (regnum lapideum).
Her beskrev han sine ideer i hovedtræk for den hierarkiske klassifikation af naturen, idet han delte den i dyreriget (regnum animale), planteriget (regnum vegetabile) og mineralriget (regnum lapideum).