ABSTRACT
IT is not so long ago that the origins of humanity were shrouded in as deep mystery as once were the sources of the Nile. Gradually, however, light has penetrated the darkness, and to-day it is possible, if not to know in detail this very distant past, at least to have such knowledge as though incomplete is yet sufficient to enable us to trace the broad outline of human development. Prehistory, which is history before history, embraces all the countries and all the centuries in which men lived before knowing how to set down in written documents what they remembered of their deeds and thoughts. Thus there exist two prehistories, one of which follows logically from the other.
