“And the frontier in here?" the North American woman had asked, tapping her forehead.
"And the frontier in here?" General Arroyo had responded, touching his heart.
"There's one frontier we only dare to cross at night," the old gringo said. "The frontier of our differences with others, of our battles with ourselves.”
The idea of frontiers is a key concept and theme in the novel. The main frontier of the text is the Mexican border, where a number of Americans cross in order to seek a new life. Firstly, the old gringo crosses the border in order to have an honorable death in Mexico fighting for the revolution. Harriet also crosses the border to seek adventure, as her old life was boring and mundane. Here, Arroyo explores the concepts of frontiers, suggesting that it is easier to cross physical frontiers than it is to deal with emotional and personal issues.
"The only way you will escape corruption is to die young."
Here, the old gringo gives us some idea about why he has traveled to Mexico, and why he wishes to die fighting. Otherwise, he suggests that he would grow old and succumb to corruption in America. As such, we learn that his wish to die fighting for the revolution in Mexico is motivated by a desire not to become corrupted by American society.
