Boldly said, this book will change the historical view of Tao philosophy. We have discovered a clear principle of Tao by a systematic analysis of the first Chapter of the Tao Te Ching. The logic of Tao philosophy is essentially the same as that of the Pre-Socratic philosopher Parmenides, the Indian and Buddhist philosopher. The author uses a very simple scientific methodology to show the logic of Tao philosophy. Most people may frown upon any systematic study of the Tao Te Ching. Therefore, any such attempt will have to face a formidable tradition of mysterious speculations about Tao. It will be difficult to convince anyone that there is a clear principle in Tao philosophy. Nevertheless, we shall show that it is an authentic philosophy of nature and Lao-tzu is a logical philosopher. Our conclusion is completely contrary to the prevailing view and is a significant and accidental discovery. We started this project without any anticipation of such a result. However, after a long period of analysis, it has become clear that there is a clear principle of Tao philosophy, with a clear logical structure. We shall carefully provide convincing evidence for the reader.