Against lax views of Socinian tendency he directed his able treatise De duabus naturis in Christo (1570).
2 Seligsohn, De duabus Hier.
In the West the works of Augustine are the great repertory for information on the subject of Manichaeism (Contra epistolam Manichaei, quam vocant fundamenti; Contra Faustum Manichaeum; Contra Fortunatum; Contra Adimantum; Contra Secundinum; De actis cum Felice Manichaeo; De genesi c. Manichaeos; De natura boni; De duabus animabus; De utilitate credendi; De moribus eccl.
He is the author of De duabus in Christo naturis adversus Eutychen et Nestorium.
Otto wrote a Chronicon, sometimes called De duabus civitatibus, an historical and philosophical work in eight books, which follows to some extent the lines laid down by Augustine and Orosius.