Hugh Etherian

Hugh Etherianus or Ugo Eteriano (Pisa, 1115–Constantinople, 1182), was an adviser on western church affairs to Byzantine emperor Manuel Comnenus. Nothing is known of his family apart from a letter sent after his death by the Pope to his brother Leo, nicknamed Tuscus, which mentions a "nephew," possibly Hugh's son. He studied under Alberic in Paris some time before 1146, then was in Constantinople from about 1165–82. He and his brother Leo Tuscus, were Tuscans by birth, employed at the court of Constantinople under the Emperor Manuel I Comnenus. Hugh was a Catholic theologian and controversialist, who became a Cardinal at the end of his life.

He is notable for his work Contra Patarenos ("Against the Patarenes") which is a treatise against Catharism surviving in two Latin manuscripts in Oxford and Seville. Latin Patareni was an alternative name for Cathars, and the text sheds light on the relationship between western European Catharism and older Byzantine dualist movements such as Bogumils.

Hugo says that he was "occupied in translating the imperial letters" (Adversus Graecos 1:20), evidently an interpreter for Latin correspondence. Hugh, who does not seem to have held any official post at court, but was a very learned theologian, had many opportunities of discussing the questions at issue between the Greek Orthodox Church and Catholics.

As a result of these disputes he wrote a work in three books: De haeresibus quas Graeci in Latinos devolvunt, sive quod Spiritus Sanctus ex utroque Patre et Filio procedit. This work, the first exhaustive and scientific defence of the Filioque, was composed in both Latin and Greek. The author sent copies to the Latin Patriarch of Antioch, Aimerikos, and to Pope Alexander III, whose letter of acknowledgment is still extant. Hugh Etherianus by this treatise obtained an important place among Catholic controversialists against the Eastern Church.

...
Wikipedia