Norman Cohn, The Pursuit of the Millennium. Revolutionary Messianism in Medieval and Reformation Europe and Its Bearing on Modern Totalitarian Movements
(1957; rpt. New York: Harper, 1961), pp. 318-319:
For what the propheta offered to his followers was not simply a chance to improve their lot and to escape from pressing anxieties — it was also, above all, the prospect of carrying out a divinely ordained mission of stupendous, unique importance. This phantasy quickly came to enthrall them in their turn. And what followed then was the formation of a group of a peculiar kind, a true prototype of a modern totalitarian party: a restlessly dynamic and utterly ruthless group which, obsessed by the apocalyptic phantasy and filled with the conviction of its own infallibility, set itself infinitely above the rest of humanity and recognised no claims save that of its own supposed mission. And finally this group might — though it did not always — succeed in imposing its leadership on the great mass of the disoriented, the perplexed and the frightened.
A boundless, millennial promise made with boundless, prophet-like conviction to a number of rootless and desperate men in the midst of a society where traditional norms and relationships are disintegrating — here, it would seem, lay the source of that peculiar subterranean fascism which subsisted as a perpetual menace to the structure of medieval society. It may be suggested that here, too, lies the source of the giant fanaticisms which in our day have convulsed the world.