But the Spatio-Temporal Agents Service – to which Valerian and Laureline belong – is in constant activity. The agents' mission is to patrol both history and the universe to safeguard earth and its empire.”
-- Narrator (Chapter 1 paragraph Frame 1)

Importance: This quote provides the reader with a look at the setting and the two main characters. It is noteworthy that the world has reached “the age of leisure” (2) but Valerian and some others are still chasing the bad guys.

Actually, no one knows exactly what happened in our past between 1986 and the 24th Century. It's a mysterious era: The dark ages of the earth. That was when traditional civilization was swept away by a cataclysm.”
-- Valerian's boss (Chapter 1 paragraph Frame 2)

Importance: Valerian's boss is telling Laureline about the earth's history as a way of explaining why Valerian has to catch Xombul. He goes on to tell about an explosion at a hydrogen bomb depot and the resulting disasters.

Who are those weirdos busy pillaging...
-- Valerian (Chapter 1 paragraph Frames 1 & 2)