Optatus, Bishop of Milevis in North Africa in the late-4th century, wrote a detailed refutation of Donatist claims to be the one true and righteous Church, an ark of purity in a world which was still corrupt, despite Constantine's support for Christianity. Donatists argued that the ministry of the Catholic Church in North Africa was invalid because it had been contaminated early in the 4th century by a bishop who had betrayed the Gospel in time of persecution by the Roman state, and that after Constantine came to power the Catholic Church had called in the Roman state to persecute the Donatists. Optatus provided a dossier of Roman official documents to support his case that the Donatists were responsible for the schism, and that they too had collaborated in time of persecution and used violence in time of schism. He preceded Augustine in arguing that the unworthiness of the minister does not invalidate the sacrament and that the Church is not an exclusive sect; and he appealed, unsuccessfully, for negotiation and for the restoration of unity. This translation, the first since 1917, mades use of modern scholarship in its annotation and introduction.