COSMAS PRESBYTER. - Bulgarian author of the 10th century. He composed a treatise against the Bogomils (v.) of the first Bulgarian empire, which is our principal source on that heresy and on himself.
According to Vaillant, he was almost a contemporary of Giovanni l'esarca: he would have lived under Pietro (927–69), son of Simeone il Grande, and would have written immediately after the collapse of Bulgaria under Byzantium (972).
The purpose of the book is to curb the enormous danger of heresy and to combat abuses. The Treatise against the Bogomils is the principal work of ancient Bulgarian literature and, awkward though it may be, it is alive and sincere, surpassing its verbose Greek models. It seems to ignore the Byzantine masters, while its horizon extends as far as Jerusalem and Rome. The title proszviter, which the author himself appears to ascribe to himself, would, according to Vaillant, designate the higher clergy. Since C. also employs it
to designate holy Fathers, such as St. Athanasius, the title would even confirm Gagov’s arguments, according to which C. was a bishop.