Hierarchical social structures mirror the medieval conception of the universe (or vice versa):

Great Chain of Being, an order created by God, not to be tampered with by man:

God

Pope

Kings

Duke

Marquess

Earl

Viscount

Baron

Baronet

Knight

Serfs

animals

birds

amphibians

insects

 

Hierarchical structures are found in medieval literature, as well:

Go on to Dante's Inferno