ONE of the most important stages in man's mastery of natural resources was the discovery of the nature and use of metals. This demanded an entirely novel complex of technological innovations, and involved the

d~velopment of new skills and new habits of thought on the part of those who had previously worked only in natural substances in their raw state. Working in stone or flint to make edge-tools calls for no more than locating and selecting the appropriate rock, and then knocking or flaking or grinding it into the required shape; the same goes for tool-making in bone or ivory or wood. The skills of ancient man while technologically in a Stone Age were therefore limited, however competently or indeed brilliantly employed. The making of pottery, which involves heating clay to a temperature sufficient to remove the water of constitution, is the first step towards producing an artificial product that does not occur in nature in that particular form, and a technical relationship between kiln-fired pottery and the earliest smelted metal seems inevitable.