He published a controversial treatise, still extant, entitled comprised, as we gather from the introduction and are expressly told by Jerome, in six books. Upon this testimony, which is fully confirmed by internal evidence, the seventh book now found in our copies has been deservedly pronounced spurious by the best judges, although stme scholars still maintain that it ought to be regarded as an appendix added by the author himself upon a revision of his work. It is certainly not a modern forgery, and was very probably composed, as Dupin suggests, by some African, as a supplement, not long after the publication of the original.

Optatus addresses his production to Parmenianus, the Donatist bishop of Carthage, in reply to an attack made by that prelate upon the Catholics, anl explains at the outset the method he intends to pursue in refuting his opponent. The object of the nrst book is, to ascertain what class of persons by justly b branded as traditors and schismatics, the former being the term uniformly applied by the Donatists to their antagonists; of the second, to ascertain what the Church is, and where it is to be found; of the third, to prove that some acts of violence and cruelty on the part of the soldiery had not been committed by the orders or with the approbation of the Catholics; of the fourth, to point out who is really to be accounted the Sinner, whose sacrifice God rejects, from whose unction we must flee; of the fifth, to inquire into the nature of baptism; of the sixth, to expose the errors and projects of the Donatists. This performance was long held in such high estimation on account of the learning, acuteness, and orthodoxy displayed, not only in reference to the particular points under discussion, but upon many general questions of doctrine and discipline, that the author was esteemed worthy of the honours of canonization, his festival being celebrated on the fourth of June. Even now the book must be regarded as a valuable contribution to the ecclesiastical history of the fourth century, and constitutes our principal source of information with regard to the origin and progress of the heresy which distracted Africa for three hundred years. [DONATUS.] The language is tolerably pure, and the style is for the most part lofty and energetic, but not unfrequently becomes turgid and harsh, while it is uniformly destitute of all grace or polish. The allegorical interpretations of Scripture constantly introduced are singularly fantastic, and the sentiments expressed with regard to free-will would in modern times be pronounced decidedly Arminian. Optatus refers in the course of his arguments (1.14) to certain state papers and other public documents, which he had subjoined in support of the statements contained in the body of the work. These have disappeared, but in the best editions we find a copious and important collection of "pieces justificatives," collected from various sources, which throw much curious light not only upon the struggles of the Donatists, but upon the practice of ancient courts and the forms of ancient diplomacy.

Of the epistles and other pieces noticed by Trithemius no trace remains.