The class system in the United States is an example of an open system. ... Mobility either upwards or downwards is more common in a class system, while in a caste system, people of different castes are traditionally in a more fixed social position throughout life, regardless of their individual abilities.
A bolder blocks the entrance, placed there by the cyclops Polyphemus.
Polyphemus= <span>Πολύφημος</span>
Odysseus= Οδυσσέας