Marius Mercator

• A writer of whom, until the last quarter of the 17th century, nothing was known except indirectly through the writings of St. Augustine.
• The letter of St. Augustine, forwarded by Albinus in 418, expresses admiration of the learning of Marius and

discusses points submitted for consideration.

• Marius Mercator appears to have been a layman, but an able theologian. His learning, zeal, and ability entitle him to a respectable place among ecclesiastical writers.
• He was a convinced anti-Pelagian. He wrote two anti- Pelagian works, now lost, which are known to have existed because he sent them to St. Augustine.
• He was born in Italy and was possibly from the same region as Julian, given the close relations with Julian’s family which are mentioned in the Commonitorium super nominee Coelestii.
• In 429, he was at a Latin monastery in Thrace where he wrote the Commonitoria.
• After the condemnation of Caelestius and Nestorius at the Council of Ephesus there is no further mention of Marius Mercator, however he is thought to have outlived the Council of Chalcedon in 451.
• From the whole of Marius Mercator’s literary activity, it seems that he wrote for ecclesiastical and imperial circles in Constantinople, then worried about the Pelagian and Nestorian question, leaving us precious Latin evidence especially of Nestorius’ thought, as well as of the Pelagian movement.

• When Julian of Eclana was lecturing at Rome in 418 in favour of Pelagiansim, Mercator replied to him, and sent his reply to St. Augustine, to whom not long afterwards Mercator forwarded a second treatise.
• Whether these two exist or not is doubtful, but a treatise

called Hypognosticon, in six books, included in vol. X. of St. Augustine’s works, has been thought to be the one in question. Five of the books treat of Pelagianism, and the sixth of Predestination.

• His works, being chiefly translations, some of them from his own writings in Greek, appear in Migne in the following order: Part I - Commonitorium super nominee Coelestii: A memorial against the doctrines of Caelestius and Julian, disciples of Pelagius, written in Greek, and presented by Mercator to the Emperor Theodosius II. - A treatise, to which the Commonitorium is a preface, against Julian, entitled Subnotationes in verba Juliani, written after the death of St. Augustine. - Translations of various works relating to Pelagianism, including the creed of Theodore of Mopsuestia. Part II - Concerning the Nestorian heresy, including extracts from Theodore of Mopsuestia, with preface and refutations by Mercator. - Extracts from Theodoret bishop of Cyrus, against St. Cyril, and from his letters, with remarks by Mercator.