The chapters of this book were given as a course of Lectures on the Modern Era Lectureship Foundation, at the University of Southern California, in April, 1929. The opening chapter is a fresh attempt to reinterpret the nature and significance of mystical experience. It carries on and aims to clarify my position in this field of religion. The other chapters are in the main historical illustrations through great personalities of the meaning and value of the mystical approach to God. It is believed that each chapter adds something further to the interpretation of mystical experience given in the first chapter, so that the book is essentially one coherent whole. - From the Introduction