And in reality, there was nothing new, either in the ideas of Mach and Avenarius, nor in the Russian Machists’ claims to possessing an update to Marxism. Marx and Engels waged many struggles against idealist revisionism, the most famous case being Engels’s polemic against Eugen Dühring. Throughout the history of the revolutionary workers movement, every now and then, some clever people thrust themselves forward with claims that they wish to bring Marxism up to date.