 In the two theses which he wrote he treated of the pedagogy of Plato and of Theodulphus, Bishop of Orléans in the time of Charlemagne; both works which marked the beginning of a literary activity surpassed by few.As hagiographer he wrote on St. John the Apostle (1869) and St. Ambrose (1871).He wrote the biographies of Saint Louise de Marillac, the foundress of the Daughters of Charity (1898); of (Madame) Saint Madeleine Sophie Barat (1876), foundress of the Ladies of the Sacred Heart; of Vicomte Armand de Melun (1880), Cardinal Pie, Bishop of Poitiers (1886), Cardinal Lavigerie (1896), Ernest Lelièvre, co-founder of the Little Sisters of the Poor (1905), and Philibert Vrau, the great Christian manufacturer (1906).