It is possible to consider ones self an educated and informed person, to be familiar with the great schools of thought and movements of history and to one day stand in front of an object that is so beautiful and so unknown that it is the cause of a quantum-shift in ones understanding. One wet Saturday afternoon several weeks ago I visited Durham University Museum of Oriental Art with my daughters. As they dressed up in the silk robes and peered at the Egyptian mummies I browsed the Chinese gallery. In one cabinet was a disc cut from pale watery green jade. It measured approximately 7 inches across and had a small round hole in the middle. The edge of the disc was notched with four perfectly symmetrical raised fins making the object look like a translucent circular saw-blade. The disc was one of the most beautiful pieces of art I have ever seen. I found the harmony of color, material and form breathtaking but I had no idea what it was, who made it or for what purpose. The label in the cabinet simply read: Jade Bi, Northern China Approximately 3000 BC. Like a thunderbolt I realised I knew nothing about China. I had a passing familiarity with the modern Chinese state, I knew a modest amount about the Terracotta Army and had possibly read something somewhere about the Warring States period but the little information I had was piece-meal, disconnected and scant. I knew nothing about the Neolithic cultures of China, nothing about the material artefacts recovered from these cultures and I had never heard of a Bi (pronounced as the English letter “B”). I did not know that circular stone discs, often cut from jade, have been found across modern China and that the Er Ya, the earliest dictionary-style Chinese reference book, gave different names to such objects according to the width of the ring but that modern archaeologists tend to refer to all of them as Bi discs. I did not know that the earliest Bi were cut without the assistance of metal tools using cutting “wires” made from animal sinew covered with sharp sand and powered by water wheels. I had no idea of the variety of Bi – notched, bulged, flanged, toothed or plain. I knew nothing of the range of stones they were made from, of the differences in size and use of collars around the central hole. I did not know that later Bi were decorated with geometric and linear patterns and to my mind are thus less beautiful that the austere, unadorned Bi of the Neolithic. But most importantly – I did not know why such magnificent, ethereal objects were made. I cannot think of anything comparable from the European Neolithic. There are certainly objects of grace and beauty – delicately knapped leaf-shaped blades or polished stone axe-heads from Great Langdale but these objects have obvious practical origins, even the thinnest ceremonial axe-head is still recognisably an axe-head whereas the Bi is an object of infinitely more craft and design that has been abstracted to the point that its function is lost to us, its secrets hidden inside its form. I read that Chinese tradition associated Bi with an encompassing circular heaven that revolved on an axis, that the Bi was juxtaposed with the Cong, a tiered cylindrical column with a squared profile that represented the earth. Zhou Rites, a book that records the sacrificial activities of the Shang and Zhou dynasties, states, "Jade is used to make six ritual objects (bi, cong, gui, zhang, huang, and hu) to be offered to Heaven, Earth, and the four directions. The blue Bi is for Heaven, and yellow cong is for Earth." The circular Bi conforms to the concept of the universe: Heaven was round, Earth square. The few descriptions I was able to find speak of Bi being handled by shamans as possessors and transmitters of sacred knowledge and being interred with the dead, often placed on the stomach or chest of the body. I found an account of the central hole being used by people to call through when they wished to speak to heaven but how much of this is recent folklore and how much reflects the intended function of Bi I do not know. Bi were high status ritual objects manufactured to exacting standards and produced in large quantities, the presence of which is evidence of an ordered society able to support a stratum of skilled artisans producing luxury objects for a ruling elite but it is still not clear exactly how the Bi functioned as a symbol of heaven? It is easy for the lazy to throw around broad, meaningless concepts such as “fertility rite” or “cosmological significance” but they bring us no closer to understanding the true purpose or function of the Bi for the people who made them. The Bi of Neolithic China are analogous to the megalithic monuments of Atlantic Europe – enigmatic and anonymous pieces of paleo-engineering that by their antiquity are open to endless interpretation and analysis. Were Bi used to open a way, to act as symbols for something that had no shape and was ineffable beyond human understanding, to divide and measure the immeasurable?