Q. What made you translate the text and the notes to the Nine Chapters of Mathematical Procedures into French? A. I laboured in the countryside during the Cultural Revolution, but I didn't give up on mathematics and history. When the movement ended in the late 1970s, I went straight into the Chinese Academy of Sciences. The academy assigned me to study the Nine Chapters of Mathematical Procedures. The book dates back to 213BC and for more than 2,000 years, it was China's most important mathematics text. Previous studies by scholars were so comprehensive that most people believed there was no new ground to break. But I delved into it anyway. In the early 1980s, I discovered the Procedures' most valuable treasure was in its notes, not in the main text; and the note-maker Liu Hui, born in 263AD, is probably the greatest mathematician in Chinese history. But the rest of the world and even the most renowned Chinese scholars, barely knew anything about him or his contributions. So in 1985, with the help of a French student, I started translating it. Why is the work important? The Procedures' main text has only about 10,000 characters. It tells you how to solve a problem but never explains why. In his notes, Liu Hui provided excellent proof, corrected mistakes and developed some revolutionary mathematical concepts that were about 1,000 years ahead of the rest of the world. But his notes are very difficult to understand, so many Chinese scholars skipped them in their research. The book has been translated into German, Japanese and Russian, yet none of those versions includes them. And its title has been translated as Nine Chapters of Mathematical Art; So most people held that Chinese mathematics was about application or craftsmanship directly drawn from experience. Chinese logic was considered inferior to that of the ancient Greeks, whose intellectual tradition is regarded by many as the origin of western science. Our translation aims to correct the misunderstanding by showing the world a masterpiece of ancient Chinese logical thinking. In the words of a British scientific historian, Liu Hui's notes have largely changed the world's perception of the Chinese intellectual tradition. The first 800 copies of the book were sold out in three months. The publisher needed to rush a second print to satisfy demand. This surprised me greatly, considering it was a maths book of more than a thousand pages and priced at Euro150 (HK$1,500). What difficulties did you encounter over the 20 years? If I had known it would be so hard, I probably would never have started the project. The translation and especially Liu Hui's notes, required me to figure out what each character and sentence meant. The equations and formulas have been written in a language form that combines with the logical process of proofs. Because some of his concepts and approaches are very different from those of today, it is hard to find the right words and expressions. But the biggest headache was the difference between various editions passed down over more than 2,000 years. A typo could take me years to figure out. What do you think made Chinese mathematics fall behind the west in the end? When Liu Hui was contemplating his mathematical proofs, China was split into three equally powerful states and people's minds were free because there was no absolute authority. Academics debated in a similar manner to the ancient Greeks. Chinese mathematics has experienced three peaks, and all these periods shared the same characteristics: the absence of authority, Confucianism was weak and societies were dynamic but fairly stable. The presence of a powerful central government in combination with a single ruling philosophy has always brought great damage to the progress of mathematics. Technology may still improve, but scientific endeavours that require independent, critical thinking stop dead. Most of the Chinese mathematical heritage was lost in the Qin, Han, Tang, Ming and Qing dynasties.