From this cursory view of the three important stages in prehistoric times, it is possible to derive mistaken notions. For example, there was never a time when stone was the only material available to man. Wood, ivory and shell were probably always known and frequently procurable. Neither is it to be supposed that each of these periods broke off abruptly or that they extended over all lands simultaneously. Quite on the contrary, stages in human development are never abrupt, and changes come about unnoticed. In nature results are slowly attained and there are no sharp distinctions between them. The three divisions of Rough and Smooth Stone and Metal Ages refer to conditions of progress--not to periods of time. The Egyptians had passed through all three stages before the dawn of history; the American Indians were in the Smooth Stone Age when Columbus discovered America; and in Central Australia there are tribes today just emerging from the Smooth Stone period. The rapidity with which a tribe passes from one to another of these stages depends upon the natural conditions of the country, contact with outside peoples and many other factors. When written records enable us to weigh the true and the false, to sift out fact from fiction and legend from verified event, several nations had come into possession of a very fair degree of civilization. They had settled homes in towns and villages, recognized some form of government, understood the uses of fire, planted crops and garnered them, spun, wove and made pottery; they had attained considerable skill in the working of metals, had domestic animals and cultivated plants; they possessed a spoken, and sometimes a written, language and had attained no little skill in decorative art. A rich legacy was this for historic ages. Surely there is interest for the historian in this remote time that lies clouded still by much uncertainty. Let us consider some of these more important attainments and try to see how naturally men grew to master them and how in obscure ages the human race travelled so far on the high road to progress. DISCOVERY OF FIRE.