Born 1842, von Hartmann was originally an officer in the Prussian army. Because of an illness, he retired from military service and took up an intensive study of philosophy. In 1869 his Philosophie des Unbewussten (Philosophy of the Unconscious) appeared, and made famous almost overnight. Of the many other works he wrote, this book remained his most famous. Rudolf Steiner describes a personal impression of von Hartmann, whom he visited in Berlin in following a philosophical correspondence with him over some. This account may be found in Chapter IX of Steiner's auto-biography. Steiner's Wahrheit und Wissenschaft (Truth and Knowledge) was dedicated to von Hartmann. Hartmann died in 1906.