According to Miller, during his early career, there were at least three ideologies which influenced Diệm's social and political views in the 1920s and 1930s. The first of these was Catholic nationalism, which Diệm inherited from his family's tradition, especially from Bishop Ngô Đình Thục, his brother, and Nguyễn Hữu Bài, who advised him to "return the seal" in 1933 to oppose French policies. The second was Diệm's understanding of Confucianism, especially through his friendship with Phan Bội Châu who argued that Confucianism's teachings could be applied to a modern Vietnam. Lastly, instructed by Ngô Đình Nhu, Diệm began to examine Personalism, which originated from French Catholicism's philosophy and then applied this doctrine as the main ideology of his regime.