How does Carlos Fuentes use imagery in The Old Gringo?

Imagery:

“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.”

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“There are people whose external reality is generous because it is transparent, because you can read everything, accept everything, understand everything about them: people who carry their own sun with them.”