In Part 2, Chapter 1, Doyle uses personification to characterize the American West as a wild, irrational, and dangerous place. This is in contrast with London, the setting of Part 1 of the novel, which Doyle characterizes as comparatively dull and dreary but also more rational and civilized:
In the central portion of the great North American Continent there lies an arid and repulsive desert, which for many a long year served as a barrier against the advance of civilisation [...] Nor is Nature always in one mood throughout this grim district. It comprises snow-capped and lofty mountains, and dark and gloomy valleys. There are swift-flowing rivers which dash through jagged cañons; and there are enormous plains, which in winter are white with snow, and in summer are grey with the saline alkali dust. They all preserve, however, the common characteristics of barrenness, inhospitality, and misery.
Here, Doyle personifies the landscape by capitalizing “Nature”—suggesting that it is a proper noun, like a first name—as well as by characterizing it as inhospitable, dangerous, and moody. He also personifies the landscape when he describes it as standing in the way of the advance of civilization, suggesting that it is not only less civilized than Sherlock Holmes’s London, but in fact actively hostile towards civilization—a wild landscape that needs to be tamed. This reflects a common view of the American West in the 19th century called "manifest destiny." This was the belief that the United States was destined by God to spread across the continent from the East Coast to the West Coast due to a perceived superiority of American culture. People who subscribed to this belief saw the American West as an untamed wilderness that it was their duty to civilize, ignoring the many Native American tribes who had inhabited the land for thousands of years.
By personifying nature as inhospitable, dangerous, and anti-civilization in this way, Doyle contributes to the overall mood of danger, wildness, and intense emotionality in this section of the novel. While Part 1 is told from the comparatively intellectual and emotionally restrained first-person point of view of Dr. Watson, Part 2 focuses on Jefferson Hope, the murderer of Enoch Drebber and Joseph Stangerson, who is driven by his love for Lucy, his intense emotions, and his desire for revenge. The extremes of the landscape—like the “snow-capped and lofty mountains, and dark and gloomy valleys,” reflect the tumultuous ups and downs of his emotional state.
