Rhajia was a dangerous dysfunction state, the "song of the sirens", of Mentats, representing the total immersion of the Mentat in the inferential consciousness.
Both Duncan Idaho and Leto Atreides II described Rhajia the movement of Infinity as expressed by Life whose movement could in fact be seen by any mortal, and similarly Grodon Orpar Playt III had called it the "Movement of Infinity", and regarded it as the final stage of the Mentat Order, a breaking of the chains of servitude to practicality, while Gilbertus Albans thought it nothing more than a a death trap, for only 30% of those who entered Rhajia re-awakened, whilst the other 70% became comatose and died.
Those who survived the state reported either no memories whatsoever or the most richly satisfying intellectual experience of their lives. Rumor had it that older Mentats near death would seek Rhajia as "The most pleasant passing" a human could be blessed with.