FOURTH CENTURY. Bishop of Milevis in Numidia and author of an untidy work known as On the Schism of the Donatists or Against Parmenian the Donatist (Bishop of Carthage). Books 1-6 were written about 367 and revised when book 7 (incomplete) was added about 385. An appendix compiled between 330 and 347 comprises ten documents important for Donatist origins. A Christmas sermon also survives. Optatus's historical and theological rebuttal of Parmenian's lost Against the Church of Traditores” advances arguments later developed by Augustine. The “endowments” (dotes) of the true church include catholicity (worldwide extension), unity (communion with the cathedra Petri of Rome and the bishops), and the holiness of God's gifts, especially the sacraments, not of a membership embracing good and evil alike. Baptism sanctifies by virtue of divine grace, not the minister's standing. Optatus's church belongs unashamedly to the Christian empire and approves its measures against schismatics.