The big question
Crisis? : the Third century. The Kingdom of Gold ; The secret of empire ; Imperial women ; King of kings ; Barbarians ; The Queen and the "necessary" emperor ; Crisis
Recovery? : the Fourth century. The Four : Diocletian and the Tetrarchy ; The Christian ; Rivals ; Enemies ; The Pagan ; Goths ; East and West
Fall? : the fifth and Sixth centuries. Barbarians and Romans : generals and rebels ; The Sister and the Eternal City ; The Hun ; Sunset on an outpost of empire ; Emperors, kings, and warlords ; West and East ; Rise and fall
A simple answer
An even simpler moral.