… is from pages xii-xiii of the 2002 Dover Publications edition of the 1896 English-language translation – The Crowd: A Study of the Popular Mind – of Gustave Le Bon’s 1895 La psychologie des foules:
History tells us, that from the moment when the moral forces on which a civilisation rested have lost their strength, its final dissolution is brought about by those unconscious and brutal crowds known, justifiably enough, as barbarians.