published in six volumes, from volume i in 1776 to volumes iv, v, vi in 1788–89. the work covers the history of the roman empire, europe, and the catholic church from 98 to 1590 ad, and discusses the decline of the roman empire in the east and its fall in the west. because of its relative objectivity and heavy use of primary sources, its methodology became a model for later historians. this led to gibbon being called the first "modern historian of ancient rome".