The Languages of Pao

The Languages of Pao is a science fiction novel by Jack Vance in which the Sapir-Whorf hypothesis is strongly true.

In this novel, the Emperor of a planet called Pao hires a consultant to make his people less wimpy. The consultant uses his unique family resources and social institutions to create several new languages. These languages make warriors, aggressive merchants, techno-wizards and etc. which then come to life and create conflicts where before, Pao was a placid planet.