BULGARO. — He is the most illustrious of the so-called Four Doctors of Bologna, who tradition holds were disciples of Irnerius, founder of the Studium.
First recorded in 1154, he took part in 1158 in the Diet of Roncaglia at the invitation of Frederick Barbarossa to define imperial regalia and municipal rights; he probably died in 1166 and was buried in the church of San Procolo in Bologna.
Highly renowned among the glossators who followed him—among others, Azzo and Accursius—B. represents in the history of the Bolognese Studium the scientific approach that had its adherents in the Bulgarists, in contrast to the other approach initiated by his contemporary and colleague Martino Gosia and followed by the Gosians. B. appears to have remained more faithful and closer in his interpretive activity to the letter of the law, whereas Martino tended to interpret texts more freely, making ample use of equity, sometimes even in a capricious manner; thus B. stands as the representative of the conservative school in opposition to Martino’s innovative school.
His vast legal learning, his critical acumen, and the elegance of his diction earned him the epithet *os aureum*; among his illustrious disciples were Rogerius, Albericus, and Johannes Bassianus. Various glosses, an apparatus to the title *De diversis regulis iuris*, and a procedural treatise *De iudiciis* have come down to us from him.