“The Cambist and Lord Iron: A Fairy Tale of Economics”, Daniel Abraham2007 (, , ; similar)⁠:

(WP; TVTropes; LW discussion; non-PDF version) 2007 short story, set in a Renaissance-esque fantasy historical setting, featuring a cambist (a money-exchanger) who is set three dangerous tasks by a bored and dissolute aristocrat. The 3 challenges illustrate principles of economics:

  1. the exchange theory of value: the value of something is what you can exchange it for in the market

  2. revealed preferences: the choices individuals and groups reveal the true value set on things, regardless of what they may say
  3. gains from trade: a trade of 2 things, which remain unchanged, can make both parties better off