distinguished among ecclesiastical writers as a most zealous antagonist of the Pelagians and the Nestorians, appears to have commenced his literary career during the pontificate of Zosimus, A. D. 218, at Rome.
There he drew up a discourse against the opinions of Coelestius, which he transmitted to Africa and received in reply an epistle from St. Augustin, still extant (Ep. cxciii. ed. Bened.). Having repaired to Constantinople about ten years afterwards, for the purpose of counteracting the designs of the banished Julianus [JULIANIUS DIDIUS], he presented his Commonitorium to Theodosius. He then became deeply involved in the controversy regarding the Incarnation, and in this found active occupation for the remainder of his life, which must have extended beyond the middle of the fifth century, since we find mention made in his writings of the Eutychians, whose name does not appear among the catalogue of heretics, until after the council of Chalcedon, held in 451. Mercator seems undoubtedly to have been a layman, but we are absolutely ignorant of every circumstance connected with his origin and personal history. Hence, in the absence of all ascertained facts, an ample field is thrown open for that unprofitable species of labour which seeks to create substance out of shadow; and here the exertions of Garnier and Gabriel Gerberon are especially conspicuous, but it would be a mere waste of time and space to recount their visions.
[W.R]