In Greek culture, the mythological story that explains the cycles of day and night is centered around the goddess Selene and the mortal Endymion. Selene, the moon goddess, falls in love with Endymion, who is placed in eternal sleep by Zeus. This relationship symbolizes the daily cycle of the moon rising and setting, representing the connection between love, sacrifice, and the passage of time. Their story encapsulates the intertwining of celestial phenomena with human emotions, reflecting the ancient Greeks' attempt to understand and narrate the natural world.