 According to Miller, Diệm "displayed Christian piety in everything from his devotional practices to his habit of inserting references to the Bible into his speeches"; he also enjoyed showing off his knowledge of classical Chinese texts.After graduating at the top of his class in 1921, Diệm followed in the footsteps of his eldest brother, Ngô Đình Khôi, joining the civil service in Thừa Thiên as a junior official.Starting from the lowest rank of mandarin, Diệm steadily rose over the next decade.