Theodore's long episcopate was marked by no striking incidents. His letters, long known to the Assyrians as the "Book of Pearls", are lost; his followers have left us few personal recollections. In 394 he attended a synod at Constantinople on a question which concerned the see of Bostra in the patriarchate of Antioch. While there, Theodore had the opportunity to preach before the emperor Theodosius I, who was then starting for his last journey to the West. The sermon made a deep impression, and Theodosius, who had sat at the feet of Ambrose and Gregory Nazianzus, declared that he had never met with such a teacher (John of Antioch, ap. Facund. ii.2). Theodosius II inherited his grandfather's respect for Theodore, and often wrote to him. Another glimpse of Theodore's episcopal life is supplied by a letter of Chrysostom to him from Cucusus (AD 404–407) (Chrys. Ep. 212). The exiled patriarch "can never forget the love of Theodore, so genuine and warm, so sincere and guileless, a love maintained from early years, and manifested but now." Chrysostom (Ep. 204) thanks him profoundly for frequent though ineffectual efforts to obtain his release, and praises their friendship in such glowing terms that Theodore's enemies at the fifth Ecumenical Council made unsuccessful efforts to deny the identity of Chrysostom's correspondent with the bishop of Mopsuestia.