This book, which will contain three volumes, is not written in sermonic or expositive form. Differences occur in the length of treatment of various subjects and this the readers should notice. Although all volumes deal with spiritual life and warfare, some sections may lay more stress on spiritual life while others may lay more on spiritual warfare. The book as a whole is prepared to serve as a guide; hence its emphasis is principally a matter of how to walk in this way rather than that of persuading people initially to take this walk. - Preface.