The Bogomils and Presbyter Cosmas

The Bulgarian Presbyter Cosmas's "Sermon" on Bogomilism (ca. 970 A.D.) is a priceless document for the history of medieval dualism, not only with respect to Bulgaria and the Byzantine Empire, but for Western Europe as well. What makes it especially valuable is that it was written by a contemporary, who encountered the heretics and heard their preaching first-hand. Cosmas's "Sermon" also offers a sweeping description of tenth-century Bulgarian life, by one who loves his country and is agitated by the social disintegration which has been accelerated by war and religious controversy. Cosmas is grieved not only by the Bogomils, whom he sees as tearing the very fabric of society apart, but also by the Bulgarian ruling classes and the clergy. A true Jeremiah, he castigates men who leave their wives and children and flee to the safety of monasteries. He also criticizes monks who travel abroad — to Rome and Jerusalem — returning home to boast of their travels. As for the rich, he asks them to make their libraries available to the less fortunate, so that knowledge may be disseminated, and the perils of heresy and ignorance diminished.

In a brief Prologue, Cosmas sets forth his motive for writing about the new heresy of a man named "Bogumil" (literally "dear to God"). Cosmas says he is rather "Bogu-ne-mil," i.e. "not dear to God." He states that of all sins heresy is the unforgivable one, since it is a sin against the Holy Spirit. He admits that he is concerned that in discussing the heresy he will further it, but write he must, in order to save other Christ loving people "from falling into their net".