The colonel went to the tailor shop to take the clandestine letter to Agustin's companions. It was his only refuge ever since his co-partisans had been killed or exiled from town and he had been converted into a man with no other occupation than waiting for the mail every Friday.
-- Narration (No One Writes to the Colonel, Part 1)

Importance: In this paragraph, the story drops its first real hint that the colonel and his dead son were both involved in acts of rebellion against the government. It also establishes the colonel's routine, increasingly significant as the narrative progresses, of checking his mail every Friday.

To the Europeans, South America is a man with a mustache, a guitar, and a gun," the doctor said, laughing over his newspaper. "They don't understand the problem.
-- The Doctor (No One Writes to the Colonel, Part 2)

Importance: In this quote, the doctor - who seems to be equal parts cynic and realist - defines a key aspect of the situation in the country...