 These political conflicts pushed Lange’s plans to publish short works for the working class into the background. He did publish two smaller works (Lange 1863b, 1865c). He was also writing his most famous book, The History of Materialism, during this time. In his Grundlegung der mathematischen Psychologie (1865b), also written during this time, he indicated that he had already finished his History of Materialism. It eventually came out in print in 1866.