a result of his work for the Kürschner edition of Goethe's works, Steiner was invited to work as an editor at the Goethe archives in Weimar. Steiner remained with the archive until 1896. As well as the introductions for and commentaries to four volumes of Goethe's scientific writings, Steiner wrote two books about Goethe's philosophy: The Theory of Knowledge Implicit in Goethe's World-Conception (1886), which Steiner regarded as the epistemological foundation and justification for his later work, and Goethe's Conception of the World (1897). During this time he also collaborated in complete editions of the works of Arthur Schopenhauer and the writer Jean Paul and wrote numerous articles for various journals. In 1891, Steiner received a doctorate in philosophy at the University of Rostock, for his dissertation discussing Fichte's concept of the ego, submitted to Heinrich von Stein, whose Seven Books of Platonism Steiner esteemed. Steiner's dissertation was later published in expanded form as Truth and Knowledge: Prelude to a Philosophy of Freedom, with a dedication to Eduard von Hartmann. Two years later, in 1894, he published Die Philosophie der Freiheit (The Philosophy of Freedom or The Philosophy of Spiritual Activity, the latter being Steiner's preferred English title), an exploration of epistemology and ethics that suggested a way for humans to become spiritually free beings. Steiner later spoke of this book as containing implicitly, in philosophical form, the entire content of what he later developed explicitly as anthroposophy. In 1896, Steiner declined an offer from Elisabeth Förster-Nietzsche to help organize the Nietzsche archive in Naumburg. Her brother, Friedrich Nietzsche, was by that time non compos mentis. Förster-Nietzsche introduced Steiner into the presence of the catatonic philosopher; Steiner, deeply moved, subsequently wrote the book Friedrich Nietzsche, Fighter for Freedom. Steiner later related that: My first acquaintance with Nietzsche's writings belongs to the year 1889. Previous to that I had never read a line of his. Upon the substance of my ideas as these find expression in The Philosophy of Spiritual Activity, Nietzsche's thought had not the least influence....Nietzsche's ideas of the 'eternal recurrence' and of 'Übermensch' remained long in my mind. For in these was reflected that which a personality must feel concerning the evolution and essential being of humanity when this personality is kept back from grasping the spiritual world by the restricted thought in the philosophy of nature characterizing the end of the 19th century....What attracted me particularly was