Isaiah Berlin on The 20th Century

THERE are, in my view, two factors that, above all others, have shaped human history in this century. One is the development of the natural sciences and technology, certainly the greatest success story of our time... . The other, without doubt, consists in the great ideological storms that have altered the lives of virtually all mankind: the Russian Revolution and its aftermath - totalitarian tyrannies of both right and left and the explosions of nationalism, racism, and, in places, of religious bigotry,which ... not one among the most perceptive social thinkers of the 19th century had ever predicted.