" Persuasion usually came first, but military strength was always the indispensable instrument of Byzantine statecraft, without which nothing else could be of much use—certainly not bribes to avert attacks, which would merely whet appetites if proffered in weakness. The upkeep of sufficient military strength was therefore the permanent, many-sided challenge that the Byzantine state had to overcome each and every day, year after year, century after century. Two essential Roman practices that the Byzantines were long able to preserve—as the western empire could not—made this possible, if only by a very small margin at times. "

― Edward N. Luttwak , The Grand Strategy of the Byzantine Empire