Final answer:
The author uses a variety of literary devices to develop the theme in the excerpt from Roughing It: Lost in the Snow.
Step-by-step explanation:
The author of the excerpt from Roughing It: Lost in the Snow uses a variety of literary devices to develop the theme. One example is imagery, where the author paints a vivid picture of the Yukon setting using descriptive language. This helps readers to understand the harshness and unforgiving nature of the environment. Another literary device used is symbolism, where the coldness and struggle against the cold represents the greater internal struggle faced by the protagonist. Through these devices, the author effectively develops the theme of human perseverance in the face of adversity.