Born in Antioch circa 350 AD, Theodore served as priest and eventual Bishop of the city of Mopsuestia. A disciple of Diodore of Tarsus (who also mentored John Chrysostom), Theodore became an important tour de force in the Antiochene school of exegesis. As Theodore was a teacher to Nestorious, many of his works were condemned posthumously at the Second Council of Constantinople (the Fifth Ecumenical Council) in 553 AD. Following his condemnation most of his early works were subsequently fragmented, though a complete syriac translation of his commentary on the Gospel of John was produced nevertheless, dating back to 460-465 AD - within 40 years of Theodore's death! While we should remain critical of Theodore's dualistic Christology, especially in light of the later Chalcedonian formula, this translation of Theodore's commentary, now available in English for the first time, remains valuable for contemporary students and lay readers seeking a deeper understanding of the ancient church's view on John's Gospel.