But there must have been inventors and leaders in primitive times, some brains more fertile than others, that made change and progress possible. Who these unknown geniuses were human records do not indicate. In modern times we single out the superiors and call them great. The inventor, the statesman, the warrior, the king, have their achievements heralded and recorded in history. The records of achievement of the great barbarous cultures, of the Assyrians, the Egyptians, and the Hebrews, centre around some king whose tomb preserves the only records, while in reality some man unknown to us was the real author of such progress as was made. The reason is that progress was so slow that the changes passed unnoticed, being the products of many minds, each adding its increment of change. Only the king or ruler who could control the mass mind and the mass labor could make sufficient spectacular demonstration worth recording, and could direct others to build a tomb or record inscriptions to perpetuate his name. _Men of Genius Cause the Mutations Which Permit Progress_.--The toiling multitudes always use the products of some inventive genius. Some individual with specialized mental traits plans something different from social usages or industrial life which changes tradition and modifies the customs and habits of the mass. Whether he be statesman, inventor, philosopher, scientist, discoverer, or military leader, he usually receives credit for the great progressive mutation which he has originated. There can be little progress without these few fertile brains, just as there could be little progress unless they were supported by the laborers who carry out the plans of the genius. While the "unknown man" is less conspicuous in the progress of the race in modern complex society, he is still a factor in all progress.