* Author's note: This book, which is to give a picture of the world and life conceptions of the nineteenth century is, in its second edition, supplemented by a brief account of the preceding philosophies insofar as they are based on an intellectual conception of the world. I have done this because I feel that the ideas of the last century are better shown in their inner significance if they are not taken by themselves, but if the highlights of thought of the preceding ages fall on them. In such an “introduction” not all the “documentary materials” can be given that must form the basis of this short sketch. If I should have the opportunity to develop the sketch into an independent book, it would become clear that the appropriate basis really exists. I also have no doubt that others who want to see in this sketch a suggestion for new viewpoints will find the documentary evidence in the historical sources that have been traditionally handed down to us.