Joachim of Fiore lived in the 12th century. Yet his ideas have had a very long shelf life, and when Cohn wrote about him, in the 1950s, they were still very much alive:
For the long-term, indirect influence of Joachim's speculations can be traced right down to the present day, and most clearly in certain 'philosophies of history' of which the Church emphatically disapproves. Horrified though the unworldly mystic would have been to see it happen, it is unmistakably the Joachite phantasy of the three ages that reappeared in, for instance, the theories of historical evolution expounded by the German idealist philosophers Lessing, Schelling Fichte, and to some extent Hegel; in Auguste Comte's idea of history as an ascent from the theological through the metaphysical up to the scientific phase, and again in the Marxian dialectic of the three stages of primitive communism, class society and a final communism which is to be the realm of freedom and in which the state will have withered away. And it is no less true - if even more paradoxical - that the phrase "The Thiid Reich", first coined in 1923 by the publicist Moeller van den Brueck and later adopted as a name for the 'new order' which was supposed to last a thousand years, would have had but little emotional significance if the phantasy of a third and most glorious dispensation had not, over the centuries, entered into the common stock of European social mythology. (Page 108-9)The final paragraph of the book:
The old religious idiom has been replaced by a secular one, and this tends to obscure what otherwise would be obvious. For it is the simple truth that, stripped of their original supernatural sanction, revolutionary millenarianism and mystical anarchism are with us still. (Page 286)One constant of the millenarian phenomenon was that the millenarian leaders almost invariably were burned at the stake, whether in the 6th century or the 16th. That no longer happens. A second constant was that before they were burned, they massacred the local Jews. Though, truth be told, one didn't need to be a millenarian to slaughter one's Jewish neighbors. You may of course contend that ideas that flourished at the center of European culture for centuries and were still thriving a mere fifty years ago, have now all disappeared, but you'd have to demonstrate how and why. Irrational thought disguising itself as rational is still rampant, and hatred of the Jews likewise, after all.
Norman Cohn, The Pursuit of the Millenium, Revolutionary Millenarians and Mystical Anarchists of the Middle Ages, Paladin, 1970. The book seems unavailable at Amazon, more the pity, but at Worldcat they'll tell you which is the library nearest to you that has it - all you need to do is tell them where you are, anywhere in the world. It has also been translated to many languages, as befits a magnificent work of history that is still a great read, more than fifty years since its first publication.