Starting from Trotsky's historical role during and after the October Revolution, Manuel Kellner develops the positions that connect Trotskyists of all factions and splinter groups at all times and in all countries. He explains the key documents of the revolutionary tradition, the discussions about strategic principles, and highlights the internationalist, global position as a prominent part of Trotskyist fundamental positions. Kellner clarifies the central concepts of 'permanent revolution' and 'entrism' and makes clear what is meant by 'united front policy.' He also raises the question of why the hopes of the Fourth International, as the spearhead of mass movements to advance worldwide revolutionary revolutions, have repeatedly been disappointed. Why has it not been possible anywhere in the world to build a revolutionary mass party? Why does the movement tend to splinter into ever smaller factions? Furthermore, Kellner traces the temporary flourishing of Trotskyist organizations during the wave of politicization in 1968 and shows how the historical turning point of 1989/90 had lasting effects on them. However, in line with the series' claim 'theorie.org,' the author does not limit himself to historical analysis and inventory but illustrates perspectives for Trotskyist ideas in global movements against globalization and social cuts through several examples.