In reality, Pope Gregory was a 15th-century leader famous for commissioning a standardized calendar (hence the name Gregorian calendar). In the novel, he appears as a computer-generated character in the medieval Europe version of the Three-Body game, where he serves a similar function—in this game, too, he is trying to predict the sun’s motion and create a reliable calendar. However, the Pope Gregory of the game is also (like Zhou and Mozi before him) a brutal, almost maniacal leader, with a penchant for killing those who displease him.