Howl's Moving Castle explores several themes common to literature. They include destiny, youth, courage and love. The first two are central to Sophie's progression. Early on, her perceived notion of destiny makes her believe that she is doomed to fail because she is the eldest of three sisters. This is in contrast to Howl, who sees himself as the master of his own fate, unafraid of what society thinks of him or what their conventions demand. Sophie's self-perceived failure is reflected in the Witch of the Waste's spell, which causes her outward appearance to become old and dull.