Northrope Frye

For constructing any work of art you need some principle of repetition or recurrence: that's what gives you rhythm in music and pattern in painting. A literature, we said, has a lot to do with identifying the human world with the natural world around it, or finding analogies between them. In nature the most obvious repeating or recurring feature is the cycle. The sun travels across the sky into the dark and comes back again; the seasons go from spring to winter and back to spring again; water goes from springs or fountains to the sea and back again in rain. Human life goes from childhood to death and back again in a new birth. A great many primitive stories and myths, then, would like to attach themselves to this cycle which stretches like a backbone through the middle of both human and natural life.

Mythologies are full of young gods or heroes who go through various successful adventures and then are deserted or betrayed and killed, and then come back to life again, suggesting in their story the movement of the sun across the sky into the dark or the progressions of the seasons through winter and spring. Sometimes they're swallowed by a huge sea monster or killed by a boar; or they wander in a strange dark underworld and then fight their way out again . . . Usually there's a female figure in the story.

Northrope Frye, from "The Educated Imagination"