What is an important theme embodied in an epic?

Themes of epic poems may change over time as different audiences interpret them. However, it is clear that we remember some epics only for their themes. For example, "Paradise Lost" is a critique of religion and political society, considering the Fall of humankind. Without these themes, the story within the narrative would not exist. Equally, the theme of war in "The Iliad", and themes of love, loss, hope for the future and xenia within "The Odyssey" and "The Aeneid" are all vital when considering the nature of the poem.