I should not like to conclude this Preface without expressly drawing the attention of readers of these seven volumes(일곱 권의 책) to what they and I owe to the twenty years of work(20년 동안) quietly accomplished at my side by Charlotte von Kirschbaum. She has devoted no less of her life and to the growth of this work than I have myself. Without her co-operation it could not have been advanced from day..