Greek Myth
Perhaps it is because Asterios has Greek heritage; perhaps it is because he is preoccupied with all things classically Greek in terms of his academic leanings and his architectural bias. Whatever the reason, one of the key themes of the book is Greek mythology and classical literature, particularly the story of Orpheus in the Underworld, a theme that the author returns to repeatedly throughout the book. Asterios journeys into a strange alternate world in his daydreams that is very similar to the Underworld in which Orpheus finds himself. There are also further references to Greek mythology and classical literature throughout the book that remind us of the basis of Asterios' upbringing and cultural frame of reference.
Nature versus Nurture
Why is Polyp the way that he is? Is it because of all the things that have happened in his life, or would he have been that way by nature anyway whatever the circumstances? This is a predominant theme in his thoughts and consequently a theme in the book as well. The role of his stillborn brother is pivotal in giving meaning to this theme, in showing that although he was never raised at all they are very similar in the way that they think and act, hinting that nature is going to overcome nurture in many cases.
Duality
Duality as a whole is a key theme in the book. There are so many dualities brought to the fore; as well as the nature versus nurture duality, we see Polyp struggling with questions of destiny and free will and whether a person is ultimately governed by their heart or their head. His Greek heritage is also seen within this theme as there is also much reference to the Dionysian versus Apollonian theological argument, throwing up the dualities within Polyp of creativity and emotion versus logic.
