Some historians such as John Julius Norwich , despite their admiration for his furthering of historical methodology , consider Gibbon 's hostile views on the Byzantine Empire flawed and blame him somewhat for the lack of interest shown in the subject throughout the 19th and early 20th centuries. John Julius Norwich , Byzantium ( New York : Knopf , 1989 ) ; Byzantium : the apogee ( London and New York : Viking Press , 1991 ) .