What did Gibbon get wrong?

In writing the history of an epoch, where have the historians of the past, granting the greatness of Gibbon and Green, and all others failed?

History has been written of great characters, men and women of wealth, not of the nation en masse, but of the princes of the aristocracy. Now, in every epoch, and increasingly so, the most important factor in evolution has not been the great character or the aristocrat, but the poor, the masses, their needs and desires—I mean history has been written of the minority, while the majority was the controlling factor in evolution.

—Coleridge in Spirit

The Twentieth Plane—A Psychic Revelation