Between these limits the empire passed from the autumnal calm of the Antonine period, through the dreadful century of anarchy between Pertinax and Diocletian, through the relative peace brought about by Diocletian's reforms, the civil wars of the sons of Constantine, the disastrous defeat of Julian, the calamities of the Gothic war, the short respite under Theodosius, the growing anarchy and misery under his incompetent sons, the three sieges of Rome and its sack by the Goths, the awful appearance of Attila and his Huns, the final submergence of the Western Empire under the barbarians, and the universal ruin which marked the close of the fifth century.

This was the temporal side of affairs.

On the spiritual, we have the silent occult growth of the early Church, the conversion of Constantine, the tremendous conflict of hostile sects, the heresy of Arius, the final triumph of Athanasius, the spread of monasticism, the extinction of paganism.

Antiquity has ended, the middle ages have begun.
Over all this immense field Gibbon moves with a striking attitude of power, which arose from his consciousness of complete preparation.
What there was to be known of his subject he felt sure that he knew.
His method of treatment is very simple, one might say primitive, but it is very effective.

He masters his materials, and then condenses and clarifies them into a broad, well-filled narrative, which is always or nearly always perfectly lucid through his skill in grouping events and characters, and his fine boldness in neglecting chronological sequence for the sake of clearness and unity of action.