Author of Geschichte des Materialsmus, History of Materialism, publ. Iserlohn, 1873-5. When professor at the University of Marburg, 1865, Lange issued his study on the workers' question. This made him famous in the circle of students of social problems in Germany at that time. A friend of the working classes, Lange strove for social justice, betterment of labor conditions, and for universal education. His life, marked by his utter sincerity and devotion to his ideals, is an outstanding example of selfless dedication to the well-being of mankind.