With his book "The Psychology of Crowds," first published in French in 1895 and translated into German by Rudolf Eisler in 1908, Le Bon became the founder of mass psychology and a significant pioneer of sociological and psychological research. He argues that the crowd, even among members of high culture, blurs the critical capacity and individuality of the individual: the single person loses themselves in the crowd and behaves purely affectively; the mass situation itself triggers gullibility and is subject to the laws of psychological contagion. The fact that these insights are alarmingly relevant in the age of angry citizens, chat forums, outrage bubbles, and social media storms shows that Le Bon still deserves a place on every bookshelf even after 125 years.