Quotes from work
Demon Princes

Demon Princes is a series of five science fiction novels by Jack Vance, which cumulatively relate the story of one Kirth Gersen as he exacts his revenge on five notorious criminals, collectively known as the Demon Princes, who carried the people of his village off into slavery during his childhood. Each novel deals with his pursuit of one of the five Princes.

“Revenge is not an ignoble motive, when it works to a productive end.”
Source: Demon Princes (1964-1981), The Star King (1964), Chapter 2 (p. 28)

“You will have useful work: the destruction of evil men. What work could be more useful?”
Source: Demon Princes (1964-1981), The Star King (1964), Chapter 2 (p. 27)

“My wealth is my shelf of books!”
Source: Demon Princes (1964-1981), The Face (1979), Chapter 14 (p. 173)