2014 Reprint of 1934 Edition. Full facsimile of the original edition. Not reproduced with Optical Recognition Software. Hermann Weyl (1885-1955) was one of the twentieth century's most important mathematicians, as well as a seminal figure in the development of quantum physics and general relativity. He was also an eloquent writer with a lifelong interest in the philosophical implications of the startling new scientific developments with which he was so involved. The lectures printed in this volume were delivered in the autumn of 1933. In this book the author presents a veritable pageant of ideas invoked by the then recent discoveries in physics. Many old ideas of philosophy are reopened and subjected to the interpretation of the findings of modern science. Chapters: Subjective Elements in Sense Perception World and Consciousness Constructive Character of Scientific Concepts and Theories Relativity Subject and Object in Quantum Physics