5Gui Gu Zi, or Wisdom of the Ghost Valley in modern English, is a compilation of Daoism philosophy and Persuasion Techniques, which were written about 2,400 years ago. Though the exact author is still a topic of debate among scholars, several trustworthy evidences points to the fact that a hidden sage, whose name was Wang Xu, lived in the ghost valley (modern He Nan in China) and composed this book that incorporated Daoism, School of Naturalists, and School of Diplomacy. Perhaps due to his belief on secrecy and mysteriousness, he meditated in solitude. However, it is said that he lived for more than one hundred years and was the mentor to some of the most distinguished political and military figures in the Warring States Period in ancient China. Su Qin, Zhang Yi, Sun Bin, and Pang Juan, to name a few. A few chapters of Gui Gu Zi is now lost due to ages, but numerous Chinese intellectuals in the past have read and annotated it. For some, it was a priceless treatise on military and diplomatic strategies that can dominate the world if used appropriately. But for others, it was nothing more than a flattering scum's pocketbook on manipulation and deception. I, as a translator, did my best to articulate each arcane word in ancient Chinese to break down the barrier of the past and present, assess its current meanings and implications, and present it in an easy and understandable way for Western audiences. This book is ideal for all people who wish to succeed in their lives and comprehend human psychology to use it as a razor-sharp edge in all relationships.