Brian Aldiss 
Non-Stop 

Curiosity was discouraged in the Greene tribe. Its members lived out their lives in cramped Quarters, hacking away at the encroaching ponics. As to where they were – that was forgotten.Roy Complain decides to find out. With the renegade priest Marapper, he moves into unmapped territory, where they make a series of discoveries which turn their universe upside-down …Non-Stop is the classic SF novel of discovery and exploration; a brilliant evocation of a familiar setting seen through the eyes of a primitive.