The book begins with a Prologue in which Nash frames the relationship between wilderness and the American mind and then explores this relationship by tracing it to its roots. The first section of the Prologue even discusses the etymology of the word “wilderness” and attempts to illustrate how the word’s earliest meaning in different European cultures influenced how the people of these cultures came to view wilderness as something to be feared.

Nash points out that wilderness is a subjective word and is not easy to define—and that some disagree about its meaning. People have projected meaning onto the word. What it means is relative, but in European cultures of the early Christian era, “wilderness” loosely meant the opposite of civilization. It is generally a place where either human beings are absent or their presence is not intrusive. Nash mentions that while “wilderness” implies familiar landscapes such as forests, modern usage encompasses the sea and even space—not just the woods beyond the edge of town.

Nash raises the question of how groups over time have tried to define “wilderness.” One group may be strict and insist on the complete absence of humans in the past or present; another group may look at the degree of human presence, acknowledging that it does not entirely alter a geographical place by itself.