This book is Mr Ren's notes and interpretation of Lao Zi, one of the most important Chinese classics. It is based on his researches on Lao Zi during over 50 years, and is thus the latest research results on this book, thus it has high academic values. Professor Ren Yuan, Ren Jiyu's daughter, translated it into English with Doctor Ken Leyton-Brown. So this book is the collaborative work of father and son, and of Chinese and foreign scholars to promote Chinese culture to the whole world.