Volume 4 features the two volumes of >Welt- und Lebensanschauungen im neunzehnten Jahrhundert< of 1900/01, a work that Steiner revised and extended significantly after his turn to esotericism and then re-published in 1914 as >Die Rätsel der Philosophie<. The work presents itself as not only a traditional history of philosophy from presocratic thought to Steiner's contemporaries, but rather as a spiritually and philosophically informed theory of the evolution of human cognition. It divides the development of philosophical thought into four major periods and outlines the potential for future evolution in human cognition by means of methodical meditative practice.