The fact that penelope waits 20 years for her husband to return to her illustrates the odyssey's theme of

The Odyssey is often cited as one of the most important pieces of literature in history, it helped create and shape the way how novels were written. It also set a system of values for Greek society to follow.

This piece of art touches a lot of different subjects and themes, some of them very personal. It makes special emphasis on values like perseverance and loyalty, this themes are reflected in Penelope's behavior but also in Odysseus'

Answer: perseverance and loyalty