PETREIUS (PEETERS), THEODORUS. – Carthusian, b. at Kempen on 17 Apr. 1560, d. at Cologne on 24 Apr. 1640. He studied philosophy at Cologne, where he entered the religious life in 1587. Prior of the Charterhouse of Dülmen (1612–19), he attended the General Chapter of his Order twice.
His output was extensive but not always critical. Principal works: *Confessio Gregoriana* (Cologne 1597, 1605); a refutation of errors using the words of St. Gregory, *Confessio Tertulliana et Cyprianiana*, with the addition of *Antidota pro eadem confessione adversus impias lutheranorum et calvinistarum criminationes* (Paris 1603); *Confessio b. Leonis Magni* (Cologne 1604); *Confessio Bernardina* (ibid. 1606; 1607); *Harmonica quattuor Occidentalis Ecclesiae doctorum confessio* (ibid. 1610). In 1640 he supervised a three-volume edition of all the works of St. Bruno. He also produced various minor works on the history and discipline of his Order, as well as Latin translations of ascetical-apologetical works by the Jesuits F. Coster and J. David.