From Sima Qian's (
司马迁) letter to Ren An 《
报任安书》, explaining why he endured castration to finish the 《
史记》:
究天人之际,
通古今之变,
成一家之言。(To investigate the boundary of heaven and man, to connect the changes of past and present, and to form the words of one school.) A foundational statement of the Chinese scholar-historian's mission.